View source for 2004 Indian Ocean earthquake and tsunami

{{short description|Earthquake and subsequent tsunami in the Indian Ocean}}
{{Redirect|Boxing Day earthquake|the 2010 Christchurch earthquake|December 2010 Christchurch earthquake}}
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{{Use British English|date=March 2017}}
{{Use dmy dates|date=October 2024}}
{{Infobox earthquake
| title = 2004 Indian Ocean earthquake and tsunami
| image = {{multiple image|border=infobox|perrow=1/2/2|total_width=300
| image1 = US Navy 050102-N-9593M-040 A village near the coast of Sumatra lays in ruin after the Tsunami that struck South East Asia.jpg
| image2 = 041231중앙119구조본부 서남아시아 지진해일 출동3.jpg
| image3 = Man searching through rubble in Meulaboh after 2004 tsunami DM-SD-06-11957.JPEG
| image4 = 2004-tsunami balanced.jpg
| image5 = Tsunami Memoral Alappadu.jpg
}}
| caption = {{hlist|'''From top, left to right''': [[Banda Aceh]], Indonesia, after the tsunami • [[South Korea|Korean]] rescue workers recovering a body under debris • a man searching through rubble in [[Meulaboh]] • people running away from the tsunami • a tsunami memorial in [[Kerala]], India}}
| isc-event = 7453151
| anss-url = official20041226005853450_30
| local-date = {{Start date and age|df=yes|2004|12|26}}<ref name="usgs">{{cite web|title=M 9.1 – 2004 Sumatra – Andaman Islands Earthquake|url=https://earthquake.usgs.gov/earthquakes/eventpage/official20041226005853450_30/executive|author=National Earthquake Information Center|publisher=United States Geological Survey|access-date=24 April 2023|date=26 December 2004|archive-date=26 September 2019|archive-url=https://web.archive.org/web/20190926105014/https://earthquake.usgs.gov/earthquakes/eventpage/official20041226005853450_30/executive|url-status=live}}</ref>
| timestamp = 2004-12-26 00:58:53
| local-time = {{Unbulleted list|07:28:53 [[UTC+06:30]]|07:58:53 [[UTC+07:00]]|08:58:53 [[UTC+08:00]]}}
| pushpin_map = Indian Ocean#Indonesia Sumatra#Earth
| depth = {{cvt|30|km}}<ref name="usgs"/>
| damage = US$15 billion<ref>{{cite web|url=http://indianoceantsunami.web.unc.edu/the-economical-impacts-and-aspects-of-the-2004-indian-ocean-tsunmai-on-indonesia/|title=Indian Ocean Tsunami – Economic Aspects|website=indianoceantsunami.web.unc.edu|access-date=4 January 2018|archive-date=18 April 2019|archive-url=https://web.archive.org/web/20190418132913/http://indianoceantsunami.web.unc.edu/the-economical-impacts-and-aspects-of-the-2004-indian-ocean-tsunmai-on-indonesia/|url-status=dead}}</ref>
| location = {{Coord|3.316|N|95.854|E|type:event_scale:50000000|display=inline,title}}<ref name="usgs"/>
| type = [[Megathrust earthquake|Megathrust]]
| tsunami = {{plainlist|
* {{cvt|15|to|30|m|sigfig=1}};<ref>{{cite web|title=Astonishing Wave Heights Among the Findings of an International Tsunami Survey Team on Sumatra|url=https://soundwaves.usgs.gov/2005/03/|publisher=United States Geological Survey|access-date=16 June 2016|archive-date=27 August 2016|archive-url=https://web.archive.org/web/20160827064707/http://soundwaves.usgs.gov/2005/03/|url-status=dead}}</ref><ref name="Paris"/>
* max. {{cvt|51|m}}<ref name="geomorphologie.revues.org">{{cite journal|last1=Paris|first1=Raphaël|last2=Cachão|first2=Mário|last3=Fournier|first3=Jérôme|last4=Voldoire|first4=Olivier|title=Nannoliths abundance and distribution in tsunami deposits: example from the December 26, 2004 tsunami in Lhok Nga (north-west Sumatra, Indonesia)|journal=Géomorphologie: Relief, Processus, Environnement|date=1 April 2010|volume=16|issue=1|pages=109–118|doi=10.4000/geomorphologie.7865|bibcode=2010GRPE...16..109P |url=http://journals.openedition.org/geomorphologie/7865|access-date=2 June 2020|archive-date=25 July 2020|archive-url=https://web.archive.org/web/20200725055443/https://journals.openedition.org/geomorphologie/7865|url-status=live|issn=1266-5304|url-access=subscription}}</ref>}}
| intensity = {{MMI|IX}}
| magnitude = 9.2–9.3 {{M|w|link=y}}
| affected = [[Countries affected by the 2004 Indian Ocean earthquake and tsunami|Indian Ocean coastline areas]]
| casualties = 227,898 dead<ref name="auto">{{Cite book|last1=Telford|first1=John|url=https://cdn.sida.se/publications/files/sida61330en-joint-evaluation-of-the-international-response-to-the-indian-ocean-tsunami.pdf|title=Joint Evaluation of the International Response to the Indian Ocean Tsunami: Synthesis Report|last2=Cosgrave|first2=John|publisher=[[Tsunami Evaluation Coalition]]|year=2006|isbn=0-85003-807-3|location=London|pages=33}}</ref><ref>{{cite web|url=https://earthquake.usgs.gov/earthquakes/world/most_destructive.php|title=Earthquakes with 50,000 or More Deaths|publisher=United States Geological Survey|archive-url=https://web.archive.org/web/20130605122458/http://earthquake.usgs.gov/earthquakes/world/most_destructive.php|archive-date=5 June 2013}}</ref>
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| duration = 10 minutes
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| citations = 
| engvar = en-UK
}}
On 26 December 2004, at 07:58:53 local time ([[UTC+07:00|UTC+7]])<!--As this sentence mentions the epicentre is off Sumatra, it is understood that "local" time refers to time in Sumatra. Most literature do not use UTC+0 timezone in an attempt to "take into account all affected countries in different time zones", likely because such notation is unhelpful.-->, a {{M|w|link=y}} 9.2–9.3 earthquake struck with its [[epicenter]] off the west coast of [[Aceh]], in northern [[Sumatra]], Indonesia. The [[Submarine earthquake|undersea]] [[megathrust earthquake]], known in the scientific community as the '''Sumatra–Andaman earthquake''',<ref name=":1">{{cite journal|last1=Lay|first1=T.|last2=Kanamori|first2=H.|last3=Ammon|first3=C.|last4=Nettles|first4=M.|last5=Ward|first5=S.|last6=Aster|first6=R.|last7=Beck|first7=S.|last8=Bilek|first8=S.|last9=Brudzinski|first9=M.|last10=Butler|first10=R.|last11=DeShon|first11=H.|last12=Ekström|first12=G.|last13=Satake|first13=K.|last14=Sipkin|first14=S.|title=The Great Sumatra-Andaman Earthquake of 26 December 2004|journal=Science|date=20 May 2005|volume=308|issue=5725|pages=1127–1133|doi=10.1126/science.1112250|pmid=15905392|bibcode=2005Sci...308.1127L|s2cid=43739943|url=http://authors.library.caltech.edu/20879/2/Lay_SOM.pdf|access-date=20 March 2019|archive-date=22 July 2021|archive-url=https://web.archive.org/web/20210722221132/https://authors.library.caltech.edu/20879/2/Lay_SOM.pdf|url-status=live}}</ref><ref>{{cite web|url=https://walrus.wr.usgs.gov/tsunami/sumatraEQ/|title=Tsunamis and Earthquakes: Tsunami Generation from the 2004 Sumatra Earthquake&nbsp;– USGS Western Coastal and Marine Geology|publisher=Walrus.wr.usgs.gov|access-date=12 August 2010|archive-date=26 December 2018|archive-url=https://web.archive.org/web/20181226114009/https://walrus.wr.usgs.gov/tsunami/sumatraEQ/|url-status=live}}</ref> was caused by a rupture along the fault boundary between the [[Burma plate|Burma Plate]] and the [[Indian plate|Indian Plate]], and reached a maximum [[Modified Mercalli intensity scale|Mercalli intensity]] of IX in some areas.

The earthquake caused a massive [[tsunami]] with waves up to {{cvt|30|m|sigfig=1}} high, commonly referred to as the '''Boxing Day tsunami,''' after the [[Boxing Day]] holiday, or the '''Asian tsunami''',<ref>{{Cite web|date=24 December 2014|title=A decade after the 2004 Asian Tsunami: recalling the turning point for disaster management|url=https://www.who.int/southeastasia/news/opinion-editorials/detail/a-decade-after-the-2004-asian-tsunami-recalling-the-turning-point-for-disaster-management|access-date=18 May 2024|publisher=World Health Organization}}</ref> which devastated communities along the surrounding coasts of the Indian Ocean, killing an estimated 227,898 people in 14 countries, especially in Aceh (Indonesia), [[Sri Lanka]], [[Tamil Nadu]] in [[India]], and [[Khao Lak]] in [[Thailand]]. The direct result was severe disruption to living conditions and commerce in coastal provinces of these and other surrounding countries. It is the deadliest tsunami in history, the [[List of natural disasters by death toll#21st century|deadliest natural disaster of the 21st century]],<ref>{{Cite book |last1=Goff |first1=James |chapter-url=https://books.google.com/books?id=Xr4cEAAAQBAJ&pg=189 |title=Tsunami: The World's Greatest Waves |last2=Dudley |first2=Walter C. |publisher=Oxford University Press |year=2021 |isbn=9780197546123 |location=New York |pages=189 |chapter=Boxing Day: The World’s Worst Disaster of the 21st Century |doi=10.1093/oso/9780197546123.001.0001}}</ref> and one of the deadliest natural disasters in recorded history.<ref>{{Cite journal|last=Satake|first=Kenji|date=13 November 2014|title=Advances in earthquake and tsunami sciences and disaster risk reduction since the 2004 Indian ocean tsunami|journal=Geoscience Letters|volume=1|issue=1|article-number=15|doi=10.1186/s40562-014-0015-7|doi-access=free|bibcode=2014GSL.....1...15S|issn=2196-4092}}</ref> It is also the worst natural disaster in the history of Indonesia, the [[Maldives]], Sri Lanka, and Thailand.<ref>{{Cite journal|last=Athukorala|first=Prema-chandra|year=2012|title=Indian Ocean Tsunami: Disaster, Generosity and Recovery|url=https://onlinelibrary.wiley.com/doi/10.1111/j.1467-8381.2012.02083.x|journal=Asian Economic Journal|volume=26|issue=3|pages=211–231|doi=10.1111/j.1467-8381.2012.02083.x|issn=1351-3958|url-access=subscription}}</ref>

The earthquake itself is the most powerful earthquake ever recorded in Asia, the strongest of the 21st century, and the [[Largest earthquakes by magnitude#Strongest earthquakes by magnitude|second-or third-most powerful globally]] since modern seismography began in 1900.<ref>{{Cite journal|last1=Gross|first1=Richard S.|last2=Chao|first2=Benjamin F.|date=1 November 2006|title=The rotational and gravitational signature of the December 26, 2004 Sumatran earthquake|journal=Surveys in Geophysics|volume=27|issue=6|pages=615–632|doi=10.1007/s10712-006-9008-1|bibcode=2006SGeo...27..615G|issn=1573-0956}}</ref>{{efn|Estimates of this earthquake are on par or smaller than the 1964 Alaska earthquake ({{M|w}} 9.2–9.3).<ref name="alaska64">{{cite anss|M 9.2 – The 1964 Prince William Sound, Alaska Earthquake|1964|iscgem869809}}</ref> Depending on estimates, it could place both earthquakes just behind the 1960 Valdivia earthquake ({{M|ww}} 9.5–9.6)<ref name="chile1960">{{cite anss|M 9.5 – 1960 Great Chilean Earthquake (Valdivia Earthquake)|1960|iscgem879136}}</ref> (i.e. both rank second largest) or one of them as the second or third largest (i.e. 1964 event ranks second followed by 2004 event and vice versa).<ref>{{cite news|title=What are the biggest historical earthquakes?|url=https://earthobservatory.sg/earth-science-education/earth-science-faqs/geology-and-tectonics/what-are-the-biggest-historical-earthquakes|access-date=21 June 2024|work=Earth Observatory of Singapore}}</ref>}} It had the longest fault rupture ever observed, between {{convert|1200|to|1300|km|mi|0}}, and had the longest duration of [[Fault (geology)|faulting]] ever observed, lasting at least ten minutes.<ref>{{cite web|url=https://www.nsf.gov/news/news_summ.jsp?cntn_id=104179|title=Analysis of the Sumatra-Andaman Earthquake Reveals Longest Fault Rupture Ever|date=19 May 2005|publisher=National Science Foundation|access-date=15 December 2016|archive-date=12 August 2021|archive-url=https://web.archive.org/web/20210812205404/https://www.nsf.gov/news/news_summ.jsp?cntn_id=104179|url-status=live}}</ref> It caused the entire planet to vibrate by as much as {{cvt|10|mm|1}},<ref>{{cite web|last=Walton|first=Marsha|url=http://edition.cnn.com/2005/TECH/science/05/19/sumatra.quake/index.html|title=Scientists: Sumatra quake longest ever recorded|publisher=CNN|date=20 May 2005|access-date=15 December 2016|archive-date=14 February 2012|archive-url=https://web.archive.org/web/20120214073430/http://edition.cnn.com/2005/TECH/science/05/19/sumatra.quake/index.html|url-status=live}}</ref> and also [[remotely triggered earthquakes]] as far away as [[Alaska]].<ref>{{cite journal|last1=West|first1=Michael|last2=Sanches|first2=John J.|last3=McNutt|first3=Stephen R.|s2cid=27869948|title=Periodically Triggered Seismicity at Mount Wrangell, Alaska, After the Sumatra Earthquake|journal=[[Science (journal)|Science]]|date=20 May 2005|volume=308|issue=5725|pages=1144–1146|pmid=15905395|bibcode=2005Sci...308.1144W|doi=10.1126/science.1112462}}</ref> Its epicentre was located between [[Simeulue]] and mainland Sumatra.<ref name="Archived">{{cite journal|last1=Nalbant|first1=Suleyman S.|last2=Steacy|first2=Sandy|last3=Sieh|first3=Kerry|last4=Natawidjaja|first4=Danny|author4-link=Danny Hilman Natawidjaja|last5=McCloskey|first5=John|title=Seismology: Earthquake risk on the Sunda trench|journal=[[Nature (journal)|Nature]]|date=9 June 2005|volume=435|issue=7043|pages=756–757|doi=10.1038/nature435756a|pmid=15944691|url=http://www.gps.caltech.edu/~sieh/pubs_docs/papers/P05b.pdf|access-date=16 May 2009|archive-url=https://web.archive.org/web/20100604092608/http://www.gps.caltech.edu/~sieh/pubs_docs/papers/P05b.pdf|archive-date=4 June 2010|url-status=dead|bibcode=2005Natur.435..756N|hdl=10220/8668|s2cid=4321796}}</ref> The plight of the [[Countries affected by the 2004 Indian Ocean earthquake and tsunami|affected people and countries]] prompted a worldwide [[Humanitarian response to the 2004 Indian Ocean earthquake|humanitarian response]], with donations totaling more than US$14 billion<ref>{{cite book|last1=Jayasuriya|first1=Sisira|last2=McCawley|first2=Peter|url=http://www.e-elgar.co.uk/Bookentry_Main.lasso?id=13668|title=The Asian Tsunami: Aid and Reconstruction after a Disaster|location=Cheltenham, UK; Northampton, MA|publisher=Edward Elgar|date=2010|isbn=978-1-84844-692-2|access-date=6 December 2010|archive-url=https://web.archive.org/web/20110722005138/http://www.e-elgar.co.uk/Bookentry_Main.lasso?id=13668|archive-date=22 July 2011|url-status=dead}}</ref> (equivalent to US${{Inflation|USD|14|2004}} billion in {{Inflation/year|index=USD}} currency).

==Earthquake==
{{2004 Indian Ocean earthquake and tsunami}}
[[File:Image=2004acehearthquake.jpg|thumb|left|[[USGS]] [[ShakeMap]] for the event]]
The 2004 Indian Ocean earthquake was initially documented as having a [[Moment magnitude scale|moment magnitude]] of 8.8. The [[United States Geological Survey]] has its official estimate of {{M|w}}9.1,<ref name="usgs-2022">{{cite web|title=Long-term ocean observing for international capacity development around tsunami early warning |url=https://www.usgs.gov/publications/long-term-ocean-observing-international-capacity-development-around-tsunami-early|publisher=United States Geological Survey|access-date=18 October 2022|archive-date=18 October 2022|archive-url=https://web.archive.org/web/20221018073633/https://www.usgs.gov/publications/long-term-ocean-observing-international-capacity-development-around-tsunami-early|url-status=live}}</ref><ref>{{Cite web |url=https://earthquake.usgs.gov/earthquakes/eventpage/official20041226005853450_30/executive |access-date=2025-05-13 |website=earthquake.usgs.gov|title=M 9.1 - 2004 Sumatra - Andaman Islands Earthquake}}</ref> but most recent studies suggest that the earthquake was {{M|w}}9.2–9.3. [[Hiroo Kanamori]] of the [[California Institute of Technology]] estimates that {{M|w}}9.2 is the most representative estimate of the earthquake's size.<ref>{{Cite journal|last=Kanamori|first=Hiroo|year=2006|title=Seismological Aspects of the December 2004 Great Sumatra-Andaman Earthquake|url=http://journals.sagepub.com/doi/10.1193/1.2201969|journal=Earthquake Spectra|volume=22|issue=3_suppl|pages=1–12|doi=10.1193/1.2201969|bibcode=2006EarSp..22....1K|issn=8755-2930|url-access=subscription}}</ref> More recent studies estimate the magnitude to be {{M|w}}9.3.<ref>{{Cite journal|last1=Tsai|first1=Victor C.|last2=Nettles|first2=Meredith|last3=Ekström|first3=Göran|last4=Dziewonski|first4=Adam M.|year=2005|title=Multiple CMT source analysis of the 2004 Sumatra earthquake|url=https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2005GL023813|journal=Geophysical Research Letters|volume=32|issue=17|article-number=2005GL023813 |doi=10.1029/2005GL023813|bibcode=2005GeoRL..3217304T|issn=0094-8276}}</ref><ref>{{Cite journal|last1=Hirata|first1=Kenji|last2=Satake|first2=Kenji|last3=Tanioka|first3=Yuichiro|last4=Kuragano|first4=Tsurane|last5=Hasegawa|first5=Yohei|last6=Hayashi|first6=Yutaka|last7=Hamada|first7=Nobuo|date=1 February 2006|title=The 2004 Indian Ocean tsunami: Tsunami source model from satellite altimetry|journal=Earth, Planets and Space|volume=58|issue=2|pages=195–201|doi=10.1186/BF03353378|doi-access=free|bibcode=2006EP&S...58..195H|issn=1880-5981}}</ref><ref>{{Cite journal|last1=Menke|first1=William|last2=Abend|first2=Hannah|last3=Bach|first3=Dalia|last4=Newman|first4=Kori|last5=Levin|first5=Vadim|date=1 November 2006|title=Review of the source characteristics of the Great Sumatra–Andaman Islands earthquake of 2004|journal=Surveys in Geophysics|volume=27|issue=6|pages=603–613|doi=10.1007/s10712-006-9013-4|bibcode=2006SGeo...27..603M|issn=1573-0956|doi-access=free}}</ref><ref>{{Cite journal|last1=Stein|first1=Seth|last2=Okal|first2=Emile A.|date=1 January 2007|title=Ultralong Period Seismic Study of the December 2004 Indian Ocean Earthquake and Implications for Regional Tectonics and the Subduction Process|url=https://pubs.geoscienceworld.org/bssa/article/97/1A/S279/146573/Ultralong-Period-Seismic-Study-of-the-December|journal=Bulletin of the Seismological Society of America|volume=97|issue=1A|pages=S279–S295|doi=10.1785/0120050617|bibcode=2007BuSSA..97S.279S|issn=1943-3573|url-access=subscription}}</ref> A 2016 study estimated the magnitude to be {{M|w}}9.25,<ref>{{Cite journal|last1=Bletery|first1=Quentin|last2=Sladen|first2=Anthony|last3=Jiang|first3=Junle|last4=Simons|first4=Mark|year=2016|title=A Bayesian source model for the 2004 great Sumatra-Andaman earthquake|url=https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2016JB012911|journal=Journal of Geophysical Research: Solid Earth|volume=121|issue=7|pages=5116–5135|doi=10.1002/2016JB012911|bibcode=2016JGRB..121.5116B|issn=2169-9313}}</ref> while a 2021 study revised its 2007 estimate of {{M|w}}9.1 to a new magnitude of {{M|w}}9.2.<ref>{{Cite journal|last1=Fujii|first1=Yushiro|last2=Satake|first2=Kenji|last3=Watada|first3=Shingo|last4=Ho|first4=Tung-Cheng|date=1 December 2021|title=Re-examination of Slip Distribution of the 2004 Sumatra–Andaman Earthquake (Mw 9.2) by the Inversion of Tsunami Data Using Green's Functions Corrected for Compressible Seawater Over the Elastic Earth|journal=Pure and Applied Geophysics|volume=178|issue=12|pages=4777–4796|doi=10.1007/s00024-021-02909-6|bibcode=2021PApGe.178.4777F |issn=1420-9136|doi-access=free}}</ref>

The [[hypocentre]] of the main earthquake was approximately {{cvt|160|km|-1}} off the western coast of northern Sumatra, in the Indian Ocean just north of [[Simeulue]] island at a depth of {{cvt|30|km}} below sea level (initially reported as {{cvt|10|km|disp=or}}). The northern section of the [[Sunda megathrust]] ruptured over a length of {{cvt|1300|km}}.<ref name="Archived"/> The earthquake (followed by the tsunami) was felt in [[Bangladesh]], [[India]], [[Malaysia]], [[Myanmar]], [[Thailand]], [[Sri Lanka]] and the [[Maldives]].<ref>{{cite journal|last1=Løvholt|first1=F.|last2=Bungum|first2=H.|last3=Harbitz|first3=C.B.|last4=Glimsdal|first4=S.|last5=Lindholm|first5=C.D.|last6=Pedersen|first6=G.|display-authors=1|title=Earthquake related tsunami hazard along the western coast of Thailand|journal=Natural Hazards and Earth System Sciences|date=30 November 2006|volume=6|issue=6|pages=979–997|doi=10.5194/nhess-6-979-2006|hdl=11250/2426119|url=https://hal.archives-ouvertes.fr/hal-00299386/file/nhess-6-979-2006.pdf|bibcode=2006NHESS...6..979L|doi-access=free|access-date=1 September 2019|archive-date=25 July 2021|archive-url=https://web.archive.org/web/20210725132236/https://hal.archives-ouvertes.fr/hal-00299386/file/nhess-6-979-2006.pdf|url-status=live}}</ref> Splay faults, or secondary "pop up faults", caused long, narrow parts of the seafloor to pop up in seconds. This rapidly increased the height and speed of the tsunami waves, destroying the nearby Indonesian town of [[Lhoknga]].<ref>{{cite journal|last1=Sibuet|first1=J.|last2=Rangin|first2=C.|last3=Le Pichon|first3=X.|last4=Singh|first4=S.|last5=Cattaneo|first5=A.|last6=Graindorge|first6=D.|last7=Klingelhoefer|first7=F.|last8=Lin|first8=J.|last9=Malod|first9=J. |last10=Maury |first10=T.|last11=Schneider|first11=J.|last12=Sultan|first12=N.|last13=Umber|first13=M.|last14=Yamaguchi|first14=H.|display-authors=1|title=26th December 2004 great Sumatra–Andaman earthquake: Co-seismic and post-seismic motions in northern Sumatra|journal=Earth and Planetary Science Letters|date=15 November 2007|volume=263|issue=1–2|pages=88–103|doi=10.1016/j.epsl.2007.09.005|url=http://wwz.ifremer.fr/drogm/content/download/36024/293289/file/2007EPSLSibuet.pdf|access-date=16 May 2009|archive-url=https://www.webcitation.org/5gsKIqvg4?url=http://wwz.ifremer.fr/drogm/content/download/36024/293289/file/2007EPSLSibuet.pdf|archive-date=19 May 2009|url-status=dead|bibcode=2007E&PSL.263...88S}}</ref>

Indonesia lies between the Pacific [[Ring of Fire]] along the northeastern islands adjacent to [[New Guinea]], and the [[Alpide belt]] that runs along the south and west from Sumatra, [[Java]], [[Bali]], [[Flores]] to [[Timor]]. The [[2002 Sumatra earthquake]] is believed to have been a [[foreshock]], preceding the main event by over two years.<ref name="Vallée">{{cite journal|last=Vallée|first=M.|year=2007|title=Rupture Properties of the Giant Sumatra Earthquake Imaged by Empirical Green's Function Analysis|journal=Bulletin of the Seismological Society of America|publisher=[[Seismological Society of America]]|volume=97|issue=1A|pages=S103–S114|doi=10.1785/0120050616|url=http://igpphome.ucsd.edu/~shearer/Files/Sumatra_Papers/vallee_bssa07.pdf|bibcode=2007BuSSA..97S.103V|access-date=10 February 2016|archive-date=10 October 2016|archive-url=https://web.archive.org/web/20161010004431/http://igpphome.ucsd.edu/~shearer/Files/Sumatra_Papers/vallee_bssa07.pdf|url-status=live}}</ref>

=== Historical comparisons ===
{{See also|List of megathrust earthquakes}}
Great earthquakes such as the 2004 Indian Ocean earthquake are generally associated with [[Megathrust earthquake|megathrust]] events in [[subduction]] zones. Their [[seismic moment]]s can account for a significant fraction of the global seismic moment across century-scale periods. Of all the moment released by earthquakes in the 100 years from 1906 through 2005, roughly one-eighth was due to the 2004 Indian Ocean earthquake.<ref name=":0">{{Cite journal|last1=Bird|first1=Peter|last2=Kreemer|first2=Corné|date=February 2015|title=Revised Tectonic Forecast of Global Shallow Seismicity Based on Version 2.1 of the Global Strain Rate Map|url=https://pubs.geoscienceworld.org/bssa/article/105/1/152-166/323426|journal=Bulletin of the Seismological Society of America|volume=105|issue=1|pages=152–166|doi=10.1785/0120140129|bibcode=2015BuSSA.105..152B|issn=0037-1106|url-access=subscription}}</ref> This quake, together with the [[1964 Alaska earthquake|Great Alaskan earthquake]] (1964) and the [[1960 Valdivia earthquake|Great Chilean earthquake]] (1960), account for almost half of the total moment.<ref name=":0" /><ref>{{Cite web|last=Callender|first=Rick|title=Cumulative Moment Mag|url=https://www.iris.edu/gallery3/general/posters/CenturyofEarthquakes/CumulativeMomentMag|access-date=20 November 2022|publisher=[[IRIS Consortium]]|archive-date=20 November 2022|archive-url=https://web.archive.org/web/20221120104338/https://www.iris.edu/gallery3/general/posters/CenturyofEarthquakes/CumulativeMomentMag|url-status=dead}}</ref>

Since 1900, the only earthquakes recorded with a greater magnitude were the 1960 Chile earthquake (magnitude 9.5) and the 1964 Alaska earthquake in [[Prince William Sound]] (magnitude 9.2). The only other recorded earthquakes of magnitude 9.0 or greater were off [[Kamchatka Peninsula|Kamchatka]], Russia, on [[1952 Severo-Kurilsk earthquake|5 November 1952]] (magnitude 9.0) and [[2011 Tōhoku earthquake and tsunami|Tōhoku, Japan (magnitude 9.1) in March 2011]]. Each of these megathrust earthquakes also spawned tsunamis in the Pacific Ocean. In comparison to the 2004 Indian Ocean earthquake, the death toll from these earthquakes and tsunamis was significantly lower, primarily because of the lower population density along the coasts near affected areas.<ref name=":1" />

Comparisons with earlier earthquakes are difficult, as earthquake strength was not measured systematically until the 1930s.<ref>{{Cite web|title=How do you determine the magnitude for an earthquake that occurred prior to the creation of the magnitude scale?|url=https://www.usgs.gov/faqs/how-do-you-determine-magnitude-earthquake-occurred-prior-creation-magnitude-scale|access-date=10 December 2022|publisher=United States Geological Survey|archive-date=10 December 2022|archive-url=https://web.archive.org/web/20221210120240/https://www.usgs.gov/faqs/how-do-you-determine-magnitude-earthquake-occurred-prior-creation-magnitude-scale|url-status=live}}</ref> However, historical earthquake strength can sometimes be estimated by examining historical descriptions of the damage caused, and the geological records of the areas where they occurred.<ref>{{Cite web|last=Palmer|first=Brian|date=14 January 2010|title=How do they measure earthquakes from 250 years ago?|url=https://slate.com/news-and-politics/2010/01/how-do-they-measure-earthquakes-from-250-years-ago.html|access-date=10 December 2022|website=Slate|archive-date=10 December 2022|archive-url=https://web.archive.org/web/20221210120243/https://slate.com/news-and-politics/2010/01/how-do-they-measure-earthquakes-from-250-years-ago.html|url-status=live}}</ref> Some examples of significant historical megathrust earthquakes are the [[1868 Arica earthquake]] in Peru and the [[1700 Cascadia earthquake]] in western North America.

===Tectonic plates===
{{Main|Plate tectonics}}

[[File:Seisme Sumatra CADRE.jpg|thumb|left|Epicentre and associated aftershocks]]
The 2004 Indian Ocean earthquake was unusually large in geographical and geological extent. An estimated {{cvt|1600|km|-2}} of [[Fault (geology)|fault surface]] slipped (or ruptured) about {{cvt|15|m|-1}} along the [[subduction]] zone where the [[Indian plate]] slides under (or subducts) the overriding Burma plate. The slip did not happen instantaneously but took place in two phases over several minutes: Seismographic and acoustic data indicate that the first phase involved a rupture about {{cvt|400|km|-1}} long and {{cvt|100|km|-1}} wide, {{cvt|30|km}} beneath the sea bed—the largest rupture ever known to have been caused by an earthquake. The rupture proceeded at about {{cvt|2.8|km/s|mi/s km/h mph|sigfig=3}}, beginning off the coast of [[Aceh]] and proceeding north-westerly over about 100 seconds. After a pause of about another 100 seconds, the rupture continued northwards towards the [[Andaman Islands|Andaman]] and [[Nicobar Islands]]. The northern rupture occurred more slowly than in the south, at about {{cvt|2.1|km/s|mi/s km/h mph}}, continuing north for another five minutes to a plate boundary where the fault type changes from subduction to [[Strike-slip fault|strike-slip]] (the two plates slide past one another in opposite directions).

The Indian plate is part of the [[Indo-Australian plate]], which underlies the Indian Ocean and [[Bay of Bengal]], and is moving north-east at an average of {{cvt|60|mm/yr}}. The India Plate meets the [[Burma plate]] (which is considered a portion of the great [[Eurasian plate]]) at the [[Sunda Trench]]. At this point, the India Plate subducts beneath the Burma plate, which carries the Nicobar Islands, the Andaman Islands, and northern Sumatra. The India Plate sinks deeper and deeper beneath the Burma plate until the increasing temperature and pressure drive [[Volatile (astrogeology)|volatiles]] out of the subducting plate. These volatiles rise into the overlying plate, causing partial melting and the formation of magma. The rising magma intrudes into the crust above and exits the Earth's crust through volcanoes in the form of a [[volcanic arc]]. The volcanic activity that results as the Indo-Australian plate subducts the Eurasian plate has created the [[Sunda Arc]].

As well as the sideways movement between the plates, the 2004 Indian Ocean earthquake resulted in a rise of the seafloor by several metres, displacing an estimated {{cvt|30|km3}} of water and triggering devastating tsunami waves. The waves radiated outwards along the entire {{cvt|1600|km|-2}} length of the rupture (acting as a [[line source]]). This greatly increased the geographical area over which the waves were observed, reaching as far as Mexico, Chile, and the Arctic. The raising of the seafloor significantly reduced the capacity of the Indian Ocean, producing a permanent rise in the global sea level by an estimated {{cvt|0.1|mm|sigfig=1}}.<ref>{{cite journal|last1=Bilham|first1=Roger|title=A Flying Start, Then a Slow Slip|journal=[[Science (journal)|Science]]|date=20 May 2005|volume=308|issue=5725|pages=1126–1127|doi=10.1126/science.1113363|pmid=15905391|bibcode=2005Sci...308.1126B|s2cid=30721065}}</ref>

===Aftershocks and other earthquakes===
{{See also|List of earthquakes in Indonesia|List of earthquakes in 2004}}
[[File:Neic slav fig72.gif|thumb|Initial earthquake and aftershocks measuring greater than 4.0 {{M|w}} from 26 December 2004 to 10 January 2005]]
Numerous [[aftershock]]s were reported off the [[Andaman Islands]], the [[Nicobar Islands]] and the region of the original epicentre in the hours and days that followed. The magnitude 8.6 [[2005 Nias–Simeulue earthquake]], which originated off the coast of the Sumatran island of [[Nias]], is not considered an aftershock, despite its proximity to the epicentre, and was most likely [[coulomb stress transfer|triggered by stress changes]] associated with the 2004 event.<ref name="USGS_2005">{{cite web|url=https://earthquake.usgs.gov/earthquakes/eqarchives/poster/2005/20050328.php|title=Poster of the Northern Sumatra Earthquake of 28 March 2005 – Magnitude 8.7|publisher=United States Geological Survey|date=22 July 2010|access-date=26 June 2011|archive-url=https://web.archive.org/web/20110514113830/http://earthquake.usgs.gov/earthquakes/eqarchives/poster/2005/20050328.php|archive-date=14 May 2011|url-status=dead}}</ref> The earthquake produced its own aftershocks (some registering a magnitude of as high as 6.9.<ref>{{Cite web|title=M 6.9 – 89&nbsp;km WSW of Singkil, Indonesia|url=https://earthquake.usgs.gov/earthquakes/eventpage/usp000dr4t/executive|access-date=26 December 2023|publisher=United States Geological Survey}}</ref>

Other aftershocks of up to magnitude 7.2<ref>{{Cite web|title=M 7.2 – 284&nbsp;km WNW of Sabang, Indonesia|url=https://earthquake.usgs.gov/earthquakes/eventpage/usp000dbg6/executive|access-date=26 December 2023|publisher=United States Geological Survey}}</ref> continued to shake the region daily for three or four months.<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/asia-pacific/4430255.stm|title=Sumatra shaken by new earthquake|publisher=BBC News|date=10 April 2005|access-date=24 December 2012|archive-date=3 November 2012|archive-url=https://web.archive.org/web/20121103182113/http://news.bbc.co.uk/2/hi/asia-pacific/4430255.stm|url-status=live}}</ref> As well as continuing aftershocks, the energy released by the original earthquake continued to make its presence felt well after the event. A week after the earthquake, its reverberations could still be measured, providing valuable scientific data about the Earth's interior.

The 2004 Indian Ocean earthquake came just three days after a [[2004 Tasman Sea earthquake|magnitude 8.1 earthquake]] in the sub-antarctic [[Auckland Islands]], an uninhabited region west of New Zealand, and [[Macquarie Island]] to Australia's south. This is unusual since earthquakes of magnitude eight or more occur only about once per year on average.<ref>{{cite web|url=https://www.usgs.gov/faq/categories/9830/3355|title=USGS Earthquake Hazards Program: FAQ|publisher=United States Geological Survey|date=10 December 2012|access-date=24 December 2012|archive-url=https://web.archive.org/web/20141120115751/http://www.usgs.gov/faq/categories/9830/3355|archive-date=20 November 2014|url-status=dead}}</ref> The [[United States Geological Survey|U.S. Geological Survey]] sees no evidence of a causal relationship between these events.<ref name="USGS_2004_FAQ">{{cite web|url=https://earthquake.usgs.gov/earthquakes/eqinthenews/2004/us2004slav/faq.php|title=Magnitude 9.1 Sumatra-Andaman Islands Earthquake FAQ|publisher=United States Geological Survey|date=29 December 2014|access-date=6 January 2015|archive-url=https://web.archive.org/web/20141213144822/http://earthquake.usgs.gov/earthquakes/eqinthenews/2004/us2004slav/faq.php|archive-date=13 December 2014|url-status=dead}}</ref>

The 2004 Indian Ocean earthquake is thought to have triggered activity in both [[Mount Leuser|Leuser Mountain]]<ref>{{cite web|last=Rinaldo|first=Aditya|url=http://www.hindustantimes.com/news/181_1317370,00050004.htm|title=Thousands flee as Indonesian volcano spews into life|work=[[Hindustan Times]]|date=12 April 2005|archive-url=https://web.archive.org/web/20060217062133/http://www.hindustantimes.com/news/181_1317370%2C00050004.htm|archive-date=17 February 2006|url-status=dead}}</ref> and [[Mount Talang]],<ref>{{cite web|url=https://apnews.com/a277ea8d5aef4b058ea7a582f7982b89/Volcano-erupts-on-same-Indonesian-island-as-earlier-quake|date=3 October 2018|author=Eileen Ng|title=Volcano erupts on same Indonesian island as earlier quake|work=AP NEWS |via=Associated Press|quote=Danny Hillman Natawidjaja, a geologist with Indonesia's Institute of Science...cited the example of the eruption of Mount Talang volcano in Indonesia's Sumatra province in April 2005, which geologists have said was connected to the devastating December 2004 Indian Ocean earthquake and tsunami.|access-date=16 February 2020|archive-date=16 February 2020|archive-url=https://web.archive.org/web/20200216231638/https://apnews.com/a277ea8d5aef4b058ea7a582f7982b89/Volcano-erupts-on-same-Indonesian-island-as-earlier-quake|url-status=live}}</ref> volcanoes in Aceh along the same range of peaks, while the [[2005 Nias–Simeulue earthquake]] sparked activity in [[Lake Toba]], a massive caldera in Sumatra.<ref>{{cite web|url=https://abcnews.go.com/Technology/wireStory?id=661767|title=Volcano on Indonesia's Sumatra Erupts|work=ABC News|location=United States|date=11 April 2005|archive-url=https://web.archive.org/web/20050919103130/https://abcnews.go.com/Technology/wireStory?id=661767|archive-date=19 September 2005}}</ref>

===Energy released===
[[File:2004 Indian Ocean earthquake.svg|thumb|right|Aftershocks of 2004 Indian Ocean earthquake]]
<!--[[File:2004-tsunami.jpg|thumb|Tsunami washing ashore in [[Ao Nang]], Thailand]]-->
The energy released on the Earth's surface (''M''<sub>e</sub>, the energy magnitude, which is the ''seismic potential for damage'') by the 2004 Indian Ocean earthquake was estimated at 1.1{{x10^|17}} [[joules]].<ref>{{cite web|url=https://neic.usgs.gov/neis/eq_depot/2004/eq_041226/neic_slav_e.html|title=USGS Energy and Broadband Solution|publisher=National Earthquake Information Center, US Geological Survey|access-date=12 August 2010|archive-url=https://web.archive.org/web/20100404013939/http://neic.usgs.gov/neis/eq_depot/2004/eq_041226/neic_slav_e.html|archive-date=4 April 2010}}</ref>

The earthquake generated a seismic oscillation of the Earth's surface of up to {{cvt|200|-|300|mm|0}}, equivalent to the effect of the [[tides|tidal forces]] caused by the Sun and Moon.{{Citation needed|date=August 2024}} The seismic waves of the earthquake were felt across the planet, as far away as the U.S. state of [[Oklahoma]], where vertical movements of {{cvt|3|mm}} were recorded.{{Citation needed|date=August 2024}} By February 2005, the earthquake's effects were still detectable as a {{cvt|20|um|mm in|sigfig=1}} complex harmonic oscillation of the Earth's surface, which gradually diminished and merged with the incessant free oscillation of the Earth more than four months after the earthquake.<ref name="Virtanen">{{cite thesis|type=Dissertation|publisher=[[University of Helsinki]]|last=Virtanen|first=Heikki|year=2006|title=Studies of earth dynamics with the superconducting gravimeter|url=http://ethesis.helsinki.fi/julkaisut/mat/fysik/vk/virtanen/studieso.pdf|access-date=21 September 2009|archive-url=https://web.archive.org/web/20110605043202/http://ethesis.helsinki.fi/julkaisut/mat/fysik/vk/virtanen/studieso.pdf|archive-date=5 June 2011|url-status=dead}}</ref>

[[File:sumatra waveform large.jpg|thumb|left|Vertical-component ground motions recorded by the [[Global Seismographic Network]] and displayed by the [[IRIS Consortium]]]]
Because of its enormous energy release and shallow rupture depth, the earthquake generated remarkable seismic ground motions around the globe, particularly due to huge [[Rayleigh wave|Rayleigh (surface) elastic waves]] that exceeded {{cvt|10|mm|sigfig=1}} in vertical amplitude everywhere on Earth. The record section plot displays vertical displacements of the Earth's surface recorded by seismometers from the IRIS/USGS Global Seismographic Network plotted with respect to time (since the earthquake initiation) on the horizontal axis, and vertical displacements of the Earth on the vertical axis (note the 1&nbsp;cm scale bar at the bottom for scale). The seismograms are arranged vertically by distance from the epicentre in degrees. The earliest, lower amplitude signal is that of the compressional [[P-wave|(P) wave]], which takes about 22 minutes to reach the other side of the planet (the [[Antipodes|antipode]]; in this case near Ecuador). The largest amplitude signals are seismic surface waves that reach the antipode after about 100 minutes. The surface waves can be clearly seen to reinforce near the antipode (with the closest seismic stations in Ecuador), and to subsequently encircle the planet to return to the epicentral region after about 200 minutes. A major aftershock (magnitude 7.1) can be seen at the closest stations starting just after the 200-minute mark. The aftershock would be considered a major earthquake under ordinary circumstances but is dwarfed by the [[mainshock]].

The shift of mass and the massive release of energy slightly altered the Earth's rotation. Weeks after the earthquake, theoretical models suggested the earthquake shortened the length of a day by 2.68 [[microseconds]], due to a decrease in the [[Oblate spheroid|oblateness]] of the Earth.<ref name="NASA">{{cite press release|last1=Cook-Anderson|first1=Gretchen|last2=Beasley|first2=Dolores|url=http://www.nasa.gov/home/hqnews/2005/jan/HQ_05011_earthquake.html|title=NASA Details Earthquake Effects on the Earth|publisher=[[National Aeronautics and Space Administration]] (NASA)|date=10 January 2005|access-date=11 January 2005|archive-date=27 January 2011|archive-url=https://web.archive.org/web/20110127163105/http://www.nasa.gov/home/hqnews/2005/jan/HQ_05011_earthquake.html|url-status=live}}</ref> It also caused the Earth to minutely "wobble" on its axis by up to {{cvt|25|mm|0}} in the direction of 145° east [[longitude]],<ref>Schechner, Sam. "[http://www.slate.com/articles/news_and_politics/explainer/2004/12/earthquakes_vs_the_earths_rotation.html Earthquakes vs. the Earth's Rotation]"; {{Webarchive|url=https://web.archive.org/web/20180612143615/http://www.slate.com/articles/news_and_politics/explainer/2004/12/earthquakes_vs_the_earths_rotation.html |date=12 June 2018 }}. ''Slate''. 27 December 2004.</ref> or perhaps by up to {{cvt|50|or|60|mm}}.<ref>{{cite news|url=http://news.xinhuanet.com/english/2004-12/29/content_2389519.htm|title=Italian scientists say Asian quakes cause Earth's axis shifted|via=[[Xinhua News Agency]]|date=29 December 2004|archive-url=https://web.archive.org/web/20090705140634/http://news.xinhuanet.com/english/2004-12/29/content_2389519.htm|archive-date=5 July 2009}}</ref> Because of tidal effects of the Moon, the length of a day increases at an average of 15 microseconds per year, so any rotational change due to the earthquake will be lost quickly. Similarly, the natural [[Chandler wobble]] of the Earth, which in some cases can be up to {{cvt|15|m|sigfig=1}}, eventually offset the minor wobble produced by the earthquake.

There was {{cvt|10|m}} movement laterally and {{cvt|4|-|5|m}} vertically along the fault line. Early speculation was that some of the smaller islands south-west of Sumatra, which is on the [[Burma plate]] (the southern regions are on the [[Sunda plate]]), might have moved south-west by up to {{cvt|36|m|-1}}, but more accurate data released more than a month after the earthquake found the movement to be about {{cvt|0.2|m|0}}.<ref>{{cite news|title=Quake moved Sumatra by only 20 centimeters: Danish scientists|date=31 January 2005|via=Agence France-Presse}}</ref> Since movement was vertical as well as lateral, some coastal areas may have been moved to below sea level. The [[Andaman and Nicobar Islands]] appear to have shifted south-west by around {{cvt|1.25|m|ftin}} and to have sunk by {{cvt|1|m|ftin}}.<ref>{{Cite news|last=Bagla|first=Pallava|work=Science Now|title=After the Earth Moved|date=28 January 2005|url=https://www.science.org/content/article/after-earth-moved|access-date=16 December 2016|archive-date=20 December 2016|archive-url=https://web.archive.org/web/20161220132403/http://www.sciencemag.org/news/2005/01/after-earth-moved|url-status=live}}</ref>

[[File:Graph of largest earthquakes 1906-2005.png|thumb|upright=1|[[Seismic moment]] release of the largest earthquakes from 1906 to 2005]]
In February 2005, the [[Royal Navy]] vessel {{HMS|Scott|H131|6}} surveyed the seabed around the earthquake zone, which varies in depth between {{cvt|1000|and|5000|m|fathom ft}}. The survey, conducted using a high-resolution, multi-beam sonar system, revealed that the earthquake had made a considerable impact on the topography of the seabed. {{convert|1500|m|ft|adj=mid|-high|sigfig=1}} thrust ridges created by previous geologic activity along the fault had collapsed, generating landslides several kilometres wide. One such landslide consisted of a single block of rock some {{cvt|100|m}} high and {{cvt|2|km}} long. The momentum of the water displaced by tectonic uplift had also dragged massive slabs of rock, each weighing millions of tonnes, as far as {{cvt|10|km|0}} across the seabed. An [[oceanic trench]] several kilometres wide was exposed in the earthquake zone.<ref>{{cite news|last=Knight|first=Will|url=https://www.newscientist.com/article.ns?id=dn6994|title=Asian tsunami seabed pictured with sonar|work=[[New Scientist]]|date=10 February 2005|archive-url=https://web.archive.org/web/20050227163829/http://www.newscientist.com/article.ns?id=dn6994|archive-date=27 February 2005}}</ref>

The [[TOPEX/Poseidon]] and [[Jason-1]] satellites happened to pass over the tsunami as it was crossing the ocean.<ref>{{cite news|url=http://www.jpl.nasa.gov/news/news.cfm?release=2005-013|title=NASA/French Satellite Data Reveal New Details of Tsunami|publisher=[[Jet Propulsion Laboratory]]/[[NASA]]|date=11 January 2005|access-date=16 December 2016|archive-url=https://web.archive.org/web/20160305182017/http://www.jpl.nasa.gov/news/news.php?release=2005-013|archive-date=5 March 2016|url-status=live}}</ref> These satellites carry radars that measure precisely the height of the water surface; anomalies in the order of {{cvt|500|mm}} were measured. Measurements from these satellites may prove invaluable for the understanding of the earthquake and tsunami.<ref>{{cite web|url=http://www.aviso.oceanobs.com/en/applications/geodesy-and-geophysics/tsunamis/index.html|title=TOPEX/Poseidon Satellite Data on 26 December 2004 tsunami in the Indian Ocean|work=Aviso|archive-url=https://web.archive.org/web/20110624101155/http://www.aviso.oceanobs.com/en/applications/geodesy-and-geophysics/tsunamis/index.html|archive-date=24 June 2011}}</ref> Unlike data from [[tide gauge]]s installed on shores, measurements obtained in the middle of the ocean can be used for computing the parameters of the source earthquake without having to compensate for the complex ways in which proximity to the coast changes the size and shape of a wave.

=== Assessment of potential earthquakes in the future ===

Before the 2004 quake there were three arguments against a large earthquake occurring in the Sumatra region. After the quake it was considered that earthquake hazard risk would need to be reassessed for regions previously thought to have low risk based on these criteria:<ref>{{Cite web|url=https://www.tectonics.caltech.edu/outreach/highlights/sumatra/rethink.html|title=Rethinking the Causes of Giant Earthquakes|website=www.tectonics.caltech.edu}}</ref>

#The subducting plate at the location of the 2004 quake is older and more dense. Before the 2004 earthquake it was thought that only the subduction of young and buoyant crust could produce giant earthquakes.
#Slow plate motion. Previously it was thought that the convergence rate had to be fast.
#Before the 2004 quake it was thought that giant earthquakes only occurred in regions without [[back-arc basin]]s.

==Tsunami==
[[File:2004IndianOceanTsunami.jpg|thumb|left|upright=1.3|The [[Wave propagation|tsunami's propagation]] took 5 hours to reach Western Australia, 7 hours to reach the Arabian Peninsula, and did not reach the South African coast until nearly 11 hours after the earthquake]]
The sudden vertical rise of the seabed by several metres during the earthquake displaced massive volumes of water, resulting in a tsunami that struck the coasts of the Indian Ocean. A tsunami that causes damage far away from its source is sometimes called a [[teletsunami]] and is much more likely to be produced by the vertical motion of the seabed than by horizontal motion.<ref>{{cite book|author1=Lorca, Emilio|author2=Recabarren, Margot|title=Earthquakes and tsunamis: high school textbook|year=1997|url=http://unesdoc.unesco.org/images/0011/001115/111576eo.pdf|access-date=16 December 2016|archive-date=29 September 2018|archive-url=https://web.archive.org/web/20180929123116/http://unesdoc.unesco.org/images/0011/001115/111576eo.pdf|url-status=live}}</ref>

The tsunami, like all the others, behaved differently in deep water than in shallow water. In deep ocean water, tsunami waves form only a low, broad hump, barely noticeable and harmless, which generally travels at the high speed of {{cvt|500|to|1000|km/h}}; in shallow water near coastlines, a tsunami slows down to only tens of kilometres per hour but, in doing so, forms large destructive waves. Scientists investigating the damage in Aceh found evidence that the wave reached a height of {{cvt|24|m|sigfig=1}} when coming ashore along large stretches of the coastline, rising to {{cvt|30|m|sigfig=1}} in some areas when travelling inland.<ref name="Paris">{{cite journal|last=Paris|first=R.|author2=Lavigne F.|author3=Wassimer P.|author4=Sartohadi J.|year=2007|title=Coastal sedimentation associated with the December 26, 2004 tsunami in Lhoknga, west Banda Aceh (Sumatra, Indonesia)|journal=Marine Geology|publisher=Elsevier|volume=238|issue=1–4|pages=93–106|doi=10.1016/j.margeo.2006.12.009|bibcode=2007MGeol.238...93P}}</ref> Radar satellites recorded the heights of tsunami waves in deep water: the maximum height was at {{cvt|600|mm|ft|sigfig=1}} two hours after the earthquake, the first such observations ever made.<ref>{{cite news|last=Leslie|first=John|url=http://www.noaanews.noaa.gov/stories2005/s2365.htm|title=NOAA Scientists able to Measure Tsunami Height from Space|work=NOAA Magazine|publisher=[[National Oceanic and Atmospheric Administration]]|date=10 January 2005|access-date=16 December 2016|archive-date=3 June 2018|archive-url=https://web.archive.org/web/20180603072630/http://www.noaanews.noaa.gov/stories2005/s2365.htm|url-status=live}}</ref><ref>{{cite news|last=McKee|first=Maggie|url=https://www.newscientist.com/article.ns?id=dn6854|title=Radar satellites capture tsunami wave height|work=[[New Scientist]]|date=6 January 2005|archive-url=https://web.archive.org/web/20080924134642/http://www.newscientist.com/article.ns?id=dn6854|archive-date=24 September 2008}}</ref>

According to [[Tad Murty]], vice-president of the Tsunami Society, the total energy of the tsunami waves was equivalent to about {{convert|5|MtonTNT|lk=on}}, which is more than twice the total explosive energy used during all of World War II (including the two atomic bombs) but still a couple of [[order of magnitude|orders of magnitude]] less than the energy released in the earthquake itself. In many places, the waves reached as far as {{cvt|2|km}} inland.<ref>{{cite news|last1=Pearce|first1=Fred|last2=Holmes|first2=Bob|url=https://www.newscientist.com/channel/being-human/mg18524825.100|title=Tsunami: The impact will last for decades|work=New Scientist|date=15 January 2005|archive-url=https://web.archive.org/web/20080417042254/http://www.newscientist.com/channel/being-human/mg18524825.100|archive-date=17 April 2008}}</ref>

Because the {{cvt|1600|km|-2}} fault affected by the earthquake was in a nearly north–south orientation, the greatest strength of the tsunami waves was in an east–west direction. [[Bangladesh]], which lies at the northern end of the [[Bay of Bengal]], had few casualties despite being a low-lying country relatively near the epicentre. It also benefited from the fact that the earthquake proceeded more slowly in the northern rupture zone, greatly reducing the energy of the water displacements in that region.

[[File:Tsunami size scale 26Dec2004.png|thumb|upright=.7|Average height of the waves]]
Coasts that have a landmass between them and the tsunami's location of origin are usually safe; however, tsunami waves can sometimes [[diffraction|diffract]] around such landmasses. Thus, the state of [[Kerala]] was hit by the tsunami despite being on the western coast of India, and the western coast of Sri Lanka suffered substantial impacts. Distance alone was no guarantee of safety, as Somalia was hit harder than Bangladesh despite being much farther away.

Because of the distances involved, the tsunami took anywhere from fifteen minutes to seven hours to reach the coastlines.<ref>{{cite web|title=Tsunami time travel map|url=http://tsun.sscc.ru/tsulab/20041226trt.htm|publisher=Tsunami Laboratory, Novosibirsk, Russia|access-date=20 July 2012|url-status=dead|archive-url=https://web.archive.org/web/20120403182951/http://tsun.sscc.ru/tsulab/20041226trt.htm|archive-date=3 April 2012}}</ref><ref>{{cite web|url=http://staff.aist.go.jp/kenji.satake/Sumatra-E.html|title=Time travel map: Active Fault Research Center: National Institute of Advanced Industrial Science and Technology, Japan|publisher=Staff.aist.go.jp|access-date=24 December 2012|url-status=dead|archive-url=https://web.archive.org/web/20120717104438/http://staff.aist.go.jp/kenji.satake/Sumatra-E.html|archive-date=17 July 2012}}</ref> The northern regions of the Indonesian island of Sumatra were hit quickly, while Sri Lanka and the east coast of India were hit roughly 90 minutes to two hours later. Thailand was struck about two hours later despite being closer to the epicentre because the tsunami travelled more slowly in the shallow [[Andaman Sea]] off its western coast.

The tsunami was noticed as far as [[Struisbaai]] in South Africa, about {{cvt|8500|km}} away, where a {{convert|1.5|m|ft|0|adj=mid|-high}} tide surged on shore about 16 hours after the earthquake. It took a relatively long time to reach Struisbaai at the southernmost point of Africa, probably because of the broad continental shelf off South Africa and because the tsunami would have followed the South African coast from east to west. The tsunami also reached Antarctica, where tidal gauges at Japan's [[Showa Base]] recorded oscillations of up to a metre ({{convert|1|m|ftin|disp=output only}}), with disturbances lasting a couple of days.<ref>{{cite web|url=http://www1.kaiho.mlit.go.jp/KANKYO/KAIYO/KOUHOU/iotunami/iotunami_eng.html|title=Indian Ocean Tsunami" at Syowa Station, Antarctica|publisher=Hydrographic and Oceanographic Dept. Japan Coast Guard|access-date=17 December 2016|archive-date=21 June 2017|archive-url=https://web.archive.org/web/20170621060542/http://www1.kaiho.mlit.go.jp/KANKYO/KAIYO/KOUHOU/iotunami/iotunami_eng.html|url-status=live}}</ref>

Some of the tsunami's energy escaped into the Pacific Ocean, where it produced small but measurable tsunamis along the western coasts of North and South America, typically around {{cvt|200|to|400|mm}}.<ref>{{cite web|url=http://wcatwc.arh.noaa.gov/IndianOSite/IndianO12-26-04.htm|title=Indian Ocean Tsunami of 26 December 2004|publisher=West Coast/Alaska Tsunami Warning Center (USGS)|date=31 December 2004|archive-url=https://web.archive.org/web/20120204070520/http://wcatwc.arh.noaa.gov/IndianOSite/IndianO12-26-04.htm|archive-date=4 February 2012}}</ref> At [[Manzanillo, Colima|Manzanillo]], Mexico, a tsunami with a wave height of {{Convert|89.3|cm|ft in}} was measured.<ref>{{Cite web |title=NCEI Hazard Runup Information |url=https://www.ngdc.noaa.gov/hazel/view/hazards/tsunami/runup-more-info/6847 |access-date=9 April 2025 |website=NOAA}}</ref> As well, the tsunami was large enough to be detected in [[Vancouver]], which puzzled many scientists, as the tsunamis measured in some parts of South America were larger than those measured in some parts of the Indian Ocean. It has been theorized that the tsunamis were focused and directed at long ranges by the [[mid-ocean ridge]]s which run along the margins of the continental plates.<ref>{{cite web|last=Carey|first=Bjorn|url=http://www.livescience.com/9314-tsunami-waves-channeled-globe-2004-disaster.html|title=Tsunami Waves Channeled Around the Globe in 2004 Disaster|work=LiveScience|date=25 August 2005|access-date=17 December 2016|archive-date=20 December 2016|archive-url=https://web.archive.org/web/20161220140730/http://www.livescience.com/9314-tsunami-waves-channeled-globe-2004-disaster.html|url-status=live}}</ref>

===Early signs and warnings===
[[File:KataNoiReceding.jpg|thumb|Maximum recession of tsunami waters at [[Kata Noi Beach]] at 10:25&nbsp;a.m., prior to the third—and strongest—tsunami wave]]
Despite a delay of up to several hours between the earthquake and the impact of the tsunami, nearly all of the victims were taken by surprise. There were no [[tsunami warning system]]s in the Indian Ocean to detect tsunamis or to warn the general population living around the ocean.<ref>{{cite web|publisher=[[Australian Geographic]]|title=The 2004 Boxing Day tsunami|date=18 December 2014|url=http://www.australiangeographic.com.au/blogs/on-this-day/2014/12/on-this-day-in-history-boxing-day-tsunami|access-date=5 March 2015|archive-date=23 February 2015|archive-url=https://web.archive.org/web/20150223020344/http://www.australiangeographic.com.au/blogs/on-this-day/2014/12/on-this-day-in-history-boxing-day-tsunami|url-status=live}}</ref> Tsunami detection is difficult because while a tsunami is in deep water, it has little height and a network of sensors is needed to detect it.

Tsunamis are more frequent in the Pacific Ocean than in other oceans because of earthquakes in the "[[Ring of Fire]]". Although the extreme western edge of the Ring of Fire extends into the Indian Ocean (the point where the earthquake struck), no warning system existed in that ocean. Tsunamis there are relatively rare despite earthquakes being relatively frequent in Indonesia. The last major tsunami was caused by the [[1883 eruption of Krakatoa]]. Not every earthquake produces large tsunamis: on 28 March 2005, a magnitude 8.7 earthquake hit roughly the same area of the Indian Ocean but did not result in a major tsunami.

The first warning sign of a possible tsunami is the earthquake itself. However, tsunamis can strike thousands of kilometres away where the earthquake is felt only weakly or not at all. Also, in the minutes preceding a tsunami strike, the sea sometimes recedes temporarily from the coast, which was observed on the eastern earthquake rupture zone such as the coastlines of Aceh, [[Phuket]] island and [[Khao Lak]] in Thailand, [[Penang]] island in Malaysia, and the [[Andaman and Nicobar islands]]. This rare sight reportedly induced people, especially children, to visit the coast to investigate and collect stranded fish on as much as {{cvt|2.5|km}} of exposed beach, with fatal results.<ref>{{cite web|last=Block|first=Melissa|url=https://www.npr.org/templates/story/story.php?storyId=4246573|title=Sri Lankans Seek Lost Relatives After Tsunami|work=[[All Things Considered]]|publisher=[[NPR]]|date=27 December 2004|access-date=20 December 2016|archive-date=23 November 2016|archive-url=https://web.archive.org/web/20161123083140/http://www.npr.org/templates/story/story.php?storyId=4246573|url-status=live}}</ref> However, not all tsunamis cause this "disappearing sea" effect. In some cases, there are no warning signs at all: the sea will suddenly swell without retreating, surprising many people and giving them little time to flee.

[[File:Tsunami wavefield for the 2004 Sumatra-Andaman earthquake.webm|thumb|left|Tsunami wave field in the [[Bay of Bengal]] an hour after the earthquake]]

One of the few coastal areas to evacuate ahead of the tsunami was on the Indonesian island of [[Simeulue]], close to the epicentre. Island folklore recounted an [[1907 Sumatra earthquake|earthquake and tsunami in 1907]], and the islanders fled to inland hills after the initial shaking and before the tsunami struck. These tales and oral folklore from previous generations may have helped the survival of the inhabitants.<ref>Campbell, Matthew; Loveard, Keith; et al. "[https://www.thetimes.com/uk/environment/article/focus-natures-timebomb-cbwdxwsd5xl Tsunami disaster: Focus: Nature's timebomb]"; [https://www.thetimes.com/uk/environment/article/focus-natures-timebomb-cbwdxwsd5xl]. ''Times Online''. 2 January 2005.</ref> On Maikhao Beach in north [[Phuket City]], Thailand, a 10-year-old British tourist named [[Tilly Smith]] had studied tsunamis in geography at school and recognised the warning signs of the receding ocean and frothing bubbles. She and her parents warned others on the beach, which was evacuated safely.<ref>{{cite news|url=https://www.telegraph.co.uk/news/1480192/Girl-10-used-geography-lesson-to-save-lives.html|title=Girl, 10, used geography lesson to save lives|newspaper=The Telegraph|date=1 January 2005|location=London|access-date=20 December 2016|archive-date=25 January 2017|archive-url=https://web.archive.org/web/20170125091359/http://www.telegraph.co.uk/news/1480192/Girl-10-used-geography-lesson-to-save-lives.html|url-status=live}}</ref> [[John Chroston]], a biology teacher from Scotland, also recognised the signs at Kamala Bay north of Phuket, taking a busload of vacationers and locals to safety on higher ground.

[[Anthropologist]]s had initially expected the [[Andamanese people|aboriginal population]] of the Andaman Islands to be badly affected by the tsunami and even feared the already depopulated [[Onge people|Onge tribe]] could have been wiped out.<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/south_asia/4135187.stm|title=Andaman aborigines' fate unclear|author=Subir Bhaumik|date=30 December 2004|publisher=BBC News|access-date=13 February 2010|archive-date=12 December 2010|archive-url=https://web.archive.org/web/20101212202153/http://news.bbc.co.uk/2/hi/south_asia/4135187.stm|url-status=live}}</ref> Many of the aboriginal tribes evacuated and suffered fewer casualties, however.<ref>{{cite journal|last1=Gupta|first1=Manu|last2=Sharma|first2=Anshu|year=2006|title=Compounded loss: the post tsunami recovery experience of Indian island communities|journal=Disaster Prevention and Management|volume=15|issue=1|pages=67–78|doi=10.1108/09653560610654248|bibcode=2006DisPM..15...67G}}</ref><ref>{{cite journal|last1=Math|first1=Suresh Bada|last2=Girimaji‌|first2=Satish Chandra|last3=Benegal|year=2006|first3=V|last4=Uday Kumar|first4=GS|last5=Hamza|first5=A|last6=Nagaraja|first6=D|title=Tsunami: Psychosocial aspects of Andaman and Nicobar islands. Assessments and intervention in the early phase|journal=[[International Review of Psychiatry]]|volume=18|pmid=16753660|issue=3|pages=233–239|doi=10.1080/09540260600656001|s2cid=10258905}}</ref> Oral traditions developed from previous earthquakes helped the aboriginal tribes escape the tsunami. For example, the folklore of the Onges talks of "huge shaking of ground followed by high wall of water". Almost all of the Onge people seemed to have survived the tsunami.<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/south_asia/4181855.stm|publisher=BBC News|first=Subir|last=Bhaumik|title=Tsunami folklore 'saved islanders'|date=20 January 2005|access-date=20 December 2016|archive-date=30 September 2009|archive-url=https://web.archive.org/web/20090930002820/http://news.bbc.co.uk/2/hi/south_asia/4181855.stm|url-status=live}}</ref>

===Indonesia===

====Aceh====
[[File:Street in downtown Banda Aceh after 2004 tsunami DD-SD-06-07372.JPEG|thumbnail|Tsunami inundation height can be seen on a house in Banda Aceh]]

The tsunami devastated the coastline of [[Aceh]] province, about 20 minutes after the earthquake. [[Banda Aceh]], the closest major city, suffered severe casualties. The sea receded and exposed the seabed, prompting locals to collect stranded fish and explore the area. Local eyewitnesses described three large waves, with the first wave rising gently to the foundation of the buildings, followed minutes later by a sudden withdrawal of the sea near the port of [[Ulèë Lheuë]]. This was succeeded by the appearance of two large black-coloured steep waves which then travelled inland into the capital city as a large turbulent bore. Eyewitnesses described the tsunami as a "black giant", "mountain" and a "wall of water". Video footage revealed torrents of black water, surging by windows of a two-story residential area situated about {{cvt|3.2|km}} inland. Additionally, amateur footage recorded in the middle of the city captured an approaching black surge flowing down the city streets, full of debris, inundating them.<ref>{{cite web|url=https://www.eeri.org/lfe/clearinghouse/sumatra_tsunami/reports/EERI_report_indonesia_jcb_2-11-05.pdf|title=Field Survey northern Sumatra and Banda Aceh, Indonesia and after the Tsunami and Earthquake of 26 December 2004|last=Borrero|first=Jose C.|place=Los Angeles|publisher=Department of Civil Engineering, University of Southern California|date=9 February 2005|access-date=20 December 2016|archive-date=10 October 2016|archive-url=https://web.archive.org/web/20161010004418/https://www.eeri.org/lfe/clearinghouse/sumatra_tsunami/reports/EERI_report_indonesia_jcb_2-11-05.pdf|url-status=live}}</ref>

[[File:PLTD Apong Ie Beuna.JPG|thumb|upright=1.1|left|''[[Apung 1]]'', a 2,600-ton vessel, was flung some {{cvt|2|km}} to {{cvt|3|km}} inland. In the years following the disaster, it became a local tourist attraction and has remained where it came to rest.]]

The level of destruction was extreme on the northwestern areas of the city, immediately inland of the aquaculture ponds, and directly facing the Indian Ocean. The tsunami height was reduced from {{cvt|12|m}} at Ulee Lheue to {{cvt|6|m}} a further {{cvt|8|km}} to the north-east. The inundation was observed to extend {{cvt|3|-|4|km|1}} inland throughout the city. Within {{cvt|2|-|3|km}} of the shoreline, houses, except for strongly-built reinforced concrete ones with brick walls, which seemed to have been partially damaged by the earthquake before the tsunami attack, were swept away or destroyed by the tsunami.<ref name="tsunami.civil.tohoku.ac.jp">{{cite web|url=http://www.tsunami.civil.tohoku.ac.jp/sumatra2004/C2.pdf|title=Chapter 2 Earthquake, Tsunami and Damage in Banda Aceh and Northern Sumatra|work=tsunami.civil.tohoku.ac.jp|access-date=20 December 2016|archive-date=15 February 2017|archive-url=https://web.archive.org/web/20170215154931/http://www.tsunami.civil.tohoku.ac.jp/sumatra2004/C2.pdf|url-status=dead}}</ref><ref name="Borreroetal2006">{{cite journal|last1=Borrero|first1=Jose C.|last2=Synolakis|first2=Costas E.|last3=Fritz|first3=Hermann|title=Northern Sumatra Field Survey after the December 2004 Great Sumatra Earthquake and Indian Ocean Tsunami|journal=Earthquake Spectra|publisher=Earthquake Engineering Research Institute|date=June 2006|volume=22|issue=S3|pages=93–104|doi=10.1193/1.2206793|bibcode=2006EarSp..22...93B|s2cid=109582188|url=http://2004tsunami.ce.gatech.edu/publications/sum_eqs_v22-iS3_127607eqs.pdf|access-date=25 September 2016|archive-date=27 September 2016|archive-url=https://web.archive.org/web/20160927005937/http://2004tsunami.ce.gatech.edu/publications/sum_eqs_v22-iS3_127607eqs.pdf|url-status=live}}</ref> The area toward the sea was wiped clean of nearly every structure, while closer to the river, dense construction in a commercial district showed the effects of severe flooding. The flow depth at the city was just at the level of the second floor, and there were large amounts of debris piled along the streets and in the ground-floor storefronts. In the seaside section of Ulee Lheue, the flow depths were over {{cvt|9|m}}. Footage showed evidence of back-flowing of the [[Aceh River]], carrying debris and people from destroyed villages at the coast and transporting them up to {{cvt|40|km}} inland.<ref>{{Cite journal|last=Borrero|first=Jose C.|date=10 June 2005|title=Field Data and Satellite Imagery of Tsunami Effects in Banda Aceh|journal=Science|volume=308|issue=5728|pages=1596|doi=10.1126/science.1110957|issn=0036-8075|pmid=15947180|s2cid=9702107}}</ref>

A group of small islands: Weh, Breueh, Nasi, [[Teunom]], [[Bunta]], [[Lumpat]], and [[Batee]] lie just north of the capital city. The tsunami reached a run-up of {{cvt|10|-|20|m}} on the western shorelines of [[Breueh Island]] and [[Nasi Island]]. Coastal villages were destroyed by the waves. On [[Weh Island]], strong surges were experienced in the port of [[Sabang, Indonesia|Sabang]], yet there was little damage with reported runup values of {{cvt|3|-|5|m}}, most likely due to the island being sheltered from the direct attack by the islands to the south-west.<ref name="Borreroetal2006"/>

[[File:Tsunami 2004 aftermath. Aceh, Indonesia, 2005. Photo- AusAID (10730623535).jpg|thumb|upright=1.1|Overturned cement carrier in Lhoknga]]

[[Lhoknga]] is a small coastal community about {{cvt|13|km}} south-west of Banda Aceh, located on a flat coastal plain in between two [[rainforest]]-covered hills, overlooking a large [[bay]] and famous for its large swathe of white sandy beach and surfing activities. The locals reported 10 to 12 waves, with the second and third being the highest and most destructive. Interviews with the locals revealed that the sea temporarily receded and exposed [[coral reefs]]. In the distant horizon, gigantic black waves about {{cvt|30|m}} high made explosion-like sounds as they broke and approached the shore. The first wave came rapidly landward from the south-west as a turbulent bore about {{cvt|0.5|-|2.5|m|ft}} high. The second and third waves were {{cvt|15|-|30|m}} high at the coast and appeared like gigantic surfing waves but "taller than the coconut trees and was like a mountain".<ref>{{cite web|url=https://www.youtube.com/watch?v=UPWlFogY7Kw|archive-url=https://web.archive.org/web/20160911033843/https://www.youtube.com/watch?v=UPWlFogY7Kw|archive-date=11 September 2016|title=Seconds From Disaster S03E13 Asian Tsunami|last=Kaget Mera|date=25 January 2016|format=Video|via=YouTube}}</ref> The second wave was the largest; it came from the west-southwest within five minutes of the first wave. The tsunami stranded cargo ships, barges and destroyed a cement mining facility near the [[Lampuuk]] coast, where it reached the fourth level of the building.<ref name="geomorphologie.revues.org"/><ref>{{cite web|url=https://www.youtube.com/watch?v=aEvk1oFGIO8|archive-url=https://ghostarchive.org/varchive/youtube/20211028/aEvk1oFGIO8|archive-date=28 October 2021|title=Great Tsunami 12-26-04 at Banda Aceh, Sumatra, Indonesia 3 of 3|author=((red17khmer))|date=30 November 2008|format=Video|via=YouTube}}{{cbignore}}</ref><ref>{{cite web|url=https://www.youtube.com/watch?v=hiD7pJl0PnA|archive-url=https://ghostarchive.org/varchive/youtube/20211028/hiD7pJl0PnA|archive-date=28 October 2021|title=Boxing Day Tsunami Banda Aceh 4 of 4|last=geoffmackley|date=19 November 2009|format=Video|via=YouTube}}{{cbignore}}</ref>

[[File:Aceh_2004_tsunami_standing_mosque_USGS.jpg|thumb|[[Baiturrahim Mosque]] survived the tsunami in [[Ulee Lheue]], [[Banda Aceh]]]]

[[Meulaboh]], a remote coastal city, was among the hardest hit by the tsunami. The waves arrived after the sea receded about {{cvt|500|m}}, followed by an advancing small tsunami. The second and third destructive waves arrived later, which exceeded the height of the coconut trees. The inundation distance is about {{cvt|5|km}}. Other towns on Aceh's west coast hit by the disaster included [[Leupung]], [[Lhokruet]], [[Lamno]], Patek, [[Calang]], and [[Teunom]]. Affected or destroyed towns on the region's north and east coast were [[Pidie Regency]], [[Samalanga]], [[Panteraja]], and [[Lhokseumawe]]. The high fatality rate in the area was mainly due to lack of preparation of the community towards a tsunami and limited knowledge and education among the population regarding the natural phenomenon. Helicopter surveys revealed entire settlements virtually destroyed, with destruction extending miles inland. Only a few mosques remained standing.<ref>{{cite web|url=http://faculty.vassar.edu/brmcadoo/yalciner-et-al-2005.pdf|last1=Yalciner|first1=A.C.|last2=Perincek|first2=D.|last3=Ersoy|first3=S.|last4=Presateya|first4=G.|last5=Hidayat|first5=R.|last6=McAdoo|first6=B.|year=2005|title=Report on December 26, 2004, Indian Ocean Tsunami, Field Survey on Jan 21–31 at North of Sumatra|publisher=ITST of UNESCO IOC|access-date=20 December 2016|archive-url=https://web.archive.org/web/20161010004216/http://faculty.vassar.edu/brmcadoo/yalciner-et-al-2005.pdf|archive-date=10 October 2016|url-status=dead}}</ref>

The greatest run-up height of the tsunami was measured at a hill between Lhoknga and [[Leupung]], on the western coast of the northern tip of Sumatra, near Banda Aceh, and reached {{cvt|51|m}}.<ref name="geomorphologie.revues.org"/><ref>{{cite web|url=http://sos.noaa.gov/Datasets/dataset.php?id=556|title=Tsunami Wave Run-ups: Indian Ocean – 2004|work=Science on a Sphere|date=31 March 2015|publisher=National Oceanic and Atmospheric Administration|access-date=20 December 2016|archive-date=30 December 2016|archive-url=https://web.archive.org/web/20161230065143/http://sos.noaa.gov/Datasets/dataset.php?id=556|url-status=live}}</ref>

The tsunami heights in Sumatra:<ref name="tsunami.civil.tohoku.ac.jp"/>
* {{cvt|15|-|30|m}} on the west coast of Aceh
* {{cvt|6|-|12|m}} on the Banda Aceh coast
* {{cvt|6|m}} on the [[Krueng Raya]] coast
* {{cvt|5|m}} on the [[Sigli]] coast
* {{cvt|3|-|6|m}} on the north coast of [[Weh Island]] directly facing the tsunami source
* {{cvt|3|m}} on the opposite side of the coast of Weh Island facing the tsunami

===Sri Lanka===
[[File:Tsunami 26-12-2004 - Kallady, Batticaloa.JPG|thumb|upright=1.1|Fishing boat stranded in [[Batticaloa]]]]
The island country of Sri Lanka, located about {{cvt|1700|km}} from Sumatra, was ravaged by the tsunami around two hours after the earthquake.<ref name="ReferenceA">{{cite report|first1=Yoshiaki|last1=Kawata|display-authors=etal|title=Comprehensive analysis of the damage and its impact on coastal zones by the 2004 Indian Ocean tsunami disaster|chapter=Chapter 3 Field Survey Report on the 2004 Indian Ocean Tsunami along the Southwestern Coast of Sri Lanka|publisher=Disaster Prev. Res. Inst.|place=Kyoto, Japan|date=2005|url=http://www.tsunami.civil.tohoku.ac.jp/sumatra2004/C3.pdf|url-status=dead|archive-url=https://web.archive.org/web/20060420195425/http://www.tsunami.civil.tohoku.ac.jp/sumatra2004/C3.pdf|archive-date=2006-04-20}}</ref> The tsunami first struck the eastern coastline and subsequently refracted around the southern point of Sri Lanka ([[Dondra Head]]). The refracted tsunami waves then inundated the southwestern part of Sri Lanka after some of its energy was reflected from impact with the Maldives.<ref name="nzsee.org.nz">{{cite journal|last1=Goff|first1=James|title=Survey of the December 26th 2004 Indian Ocean tsunami in Sri Lanka|journal=Bulletin of the New Zealand Society for Earthquake Engineering|date=December 2005|volume=38|issue=4|pages=235–244|doi=10.5459/bnzsee.38.4.235-244|url=http://www.nzsee.org.nz/db/Bulletin/Archive/38(4)0235.pdf|doi-access=free|bibcode=2005BNZSE..38..235G |access-date=3 April 2016|archive-date=27 January 2016|archive-url=https://web.archive.org/web/20160127111126/http://www.nzsee.org.nz/db/Bulletin/Archive/38(4)0235.pdf|url-status=live}}</ref>  Civilian casualties here were second only to those in Indonesia, with approximately 35,000 killed. The eastern shores of the country were the hardest hit since it faced the epicentre of the earthquake, while the southwestern shores were hit later, but the death toll was just as severe. The southwestern shores are a hotspot for tourists and fishing.<ref name="ReferenceC">{{cite web|url=http://academic.evergreen.edu/g/grossmaz/HELGESTJ/|title=Tsunami Disaster in Sri Lanka|last=Helgeson|first=T.J.|work=Waves of Devastation|publisher=University of Wisconsin-Eau Claire|date=Spring 2005|archive-url=https://web.archive.org/web/20080617101155/http://academic.evergreen.edu/g/grossmaz/HELGESTJ/|archive-date=17 June 2008}}</ref> The [[Environmental degradation|degradation of the natural environment]] in Sri Lanka contributed to the high death tolls. Approximately 90,000 buildings and many wooden houses were destroyed.<ref name="ReferenceC"/>

The tsunami arrived on the island as a small brown-orange-coloured flood. Moments later, the ocean floor was exposed for as much as {{cvt|1|km}} in places, which was followed by massive second and third waves. Amateur video recorded at the city of [[Galle]] showed a large deluge flooding the city, carrying debris and sweeping away people while in the coastal resort town of [[Beruwala]], the tsunami appeared as a huge brown-orange-coloured bore which reached the first level of a hotel, causing destruction and taking people unaware. Other videos recorded showed that the tsunami appeared like a flood raging inland. The construction of seawalls and breakwaters reduced the power of waves at some locations.

The largest run-up measured was at {{cvt|12.5|m}} with inundation distance of {{cvt|390|-|1500|m}} in [[Yala National Park|Yala]].<ref name="earthquakespectra.org">{{cite journal|title=Sri Lanka Field Survey after the December 2004 Indian Ocean Tsunami|journal=Earthquake Spectra|first1=James|last1=Goff|first2=Philip L-F.|last2=Liu|first3=Bretwood|last3=Higman|first4=Robert|last4=Morton|first5=Bruce E.|last5=Jaffe|first6=Harindra|last6=Fernando|first7=Patrick|last7=Lynett|first8=Hermann|last8=Fritz|first9=Costas|last9=Synolakis|first10=Starin|last10=Fernando|display-authors=1|volume=22|issue=S3|pages=155–172|doi=10.1193/1.2205897|year=2006|bibcode=2006EarSp..22..155G|s2cid=220297852}}</ref> In [[Hambantota]], run-ups measured {{cvt|11|m}} with the greatest inundation distance of {{cvt|2|km}}. Run-up measurements along the Sri Lankan coasts are at {{cvt|2.4|-|4.11|m}}.<ref name="earthquakespectra.org"/><ref name="nzsee.org.nz"/> Waves measured on the east coast ranged from {{cvt|4.5|-|9|m}} at [[Pottuvill]] to [[Batticaloa]] at {{cvt|2.6|-|5|m}} in the north-east around [[Trincomalee]] and {{cvt|4|-|5|m}} in the west coast from [[Moratuwa]] to [[Ambalangoda]].

Sri Lanka tsunami height survey:<ref name="ReferenceA"/><ref name="faculty.vassar.edu"/>
* {{cvt|9|m}} at [[Koggala]]
* {{cvt|6|m}} at Galle port
* {{cvt|4.8|m}} around the Galle coast
* {{cvt|8.7|m}} at [[Nonagama]]
* {{cvt|4.9|m}} at [[Weligama]]
* {{cvt|4|m}} at [[Dodanduwa]]
* {{cvt|4.7|m}} at Ambalangoda
* {{cvt|4.7|m}} at [[Hikkaduwa]] Fishery Harbour
* {{cvt|10|m}} at [[Kahawa]]
* {{cvt|4.8|m}} at North Beach of [[Beruwala]]
* {{cvt|6|m}} at [[Paiyagala]]

A regular passenger train operating between [[Maradana]] and [[Matara, Sri Lanka|Matara]] with over 1,750 passengers was [[2004 Sri Lanka tsunami-rail disaster|derailed and subsequently overturned by the tsunami]], claiming at least 1,000 lives in the largest single rail disaster death toll in history.<ref>{{cite journal|url=https://www.researchgate.net/publication/7795709|title=Observations by the International Tsunami Survey Team in Sri Lanka|journal=Science|first=P. L.-F.|last=Liu|date=1 July 2005|volume=308|issue=5728|pages=1595|doi=10.1126/science.1110730|pmid=15947179|bibcode=2005Sci...308.1595L |s2cid=11312069}}</ref> Estimates based on the state of the shoreline and a high-water mark on a nearby building place the tsunami {{cvt|7.5|-|9|m}} above sea level and {{cvt|2|-|3|m}} higher than the top of the train.<ref name="ReferenceA"/>

===Thailand===
The tsunami travelled eastward through the [[Andaman Sea]] and hit the south-western coasts of [[Thailand]], about 2 hours after the earthquake. Located about {{cvt|500|km}} from the epicentre, at the time, the region was popular with tourists because of Christmas. Many of these tourists were caught off-guard by the tsunami, as they had no prior warning. The tsunami hit during [[high tide]]. Major locations damaged included the western shores of [[Phuket]] island, the resort town of [[Khao Lak]] in Phang Nga Province, the coastal provinces of [[Krabi Province|Krabi]], [[Satun Province|Satun]], [[Ranong Province|Ranong]] and [[Trang Province|Trang]] and small offshore islands like Ko Racha Yai, the [[Phi Phi]] islands, the [[Surin Islands]] and the [[Similan Islands|Similan archipelago]]. Approximately 8,000 people were killed.

Thailand experienced the second largest tsunami run-up. The tsunami heights recorded:<ref name="ReferenceB"/><ref name="marine.tmd.go.th">{{cite journal|url=http://www.marine.tmd.go.th/Presentation/Alexandria/The%202004%20Indian%20tsunami%20in%20Thailand%20Surveyed%20runup%20heights%20and%20tide%20gauge%20records.pdf|title=The 2004 Indian tsunami in Thailand: Surveyed runup heights and tide gauge records|first1=Yoshinobu|last1=Tsuji|first2=Yuichi|last2=Namegaya|first3=Hiroyuki|last3=Matsumoto|first4=Sin-Iti|last4=Iwasaki|first5=Wattana|last5=Kanbua|first6=Mongkonkorn|last6=Sriwichai|first7=Vorawit|last7=Meesuk|display-authors=1|journal=Earth Planets Space|volume=58|issue=2|pages=223–232|year=2006|doi=10.1186/BF03353382|bibcode=2006EP&S...58..223T|s2cid=23896058|doi-access=free|access-date=3 August 2016|archive-date=21 September 2016|archive-url=https://web.archive.org/web/20160921045321/http://www.marine.tmd.go.th/Presentation/Alexandria/The%202004%20Indian%20tsunami%20in%20Thailand%20Surveyed%20runup%20heights%20and%20tide%20gauge%20records.pdf|url-status=live}}</ref>
[[File:Khao Lak Police Boat 813.jpg|thumb|upright=1.1|[[Thai Navy]] boat stranded almost {{cvt|2|km}} inland]]
* {{cvt|6|-|10|m}} in Khao Lak
* {{cvt|3|-|6|m}} along the west coast of Phuket island
* {{cvt|3|m}} along the south coast of Phuket island
* {{cvt|2|m}} along the east coast of Phuket island
* {{cvt|4|-|6|m}} on the Phi Phi Islands
* {{cvt|19.6|m}} at Ban Thung Dap
* {{cvt|5|m}} at Ramson
* {{cvt|6.8|m}} at Ban Thale Nok
* {{cvt|5|m}} at Hat Praphat (Ranong Coastal Resources Research Station)
* {{cvt|6.3|m}} at [[Thai Mueang District]]
* {{cvt|6.8|m}} at Rai Dan

The province of Phang Nga was the most affected area in [[Thailand]]. The quiet resort town of [[Khao Lak]] is located on a stretch of golden sandy beach, famed for its hotels overlooking the [[Andaman Sea]] and hilly [[rainforests]]. A video, taken by a local restaurant manager from a hill adjacent to the beach, showed that the tsunami's arrival was preceded by a sudden retreat of the sea exposing the seafloor. Many tourists and locals can be seen trying to gather fish. Moments later, the tsunami arrives as a wall of foaming water that slams into the coast, washing away numerous people who had no time to escape. Another amateur video, captured by a German family at beach level, showed the tsunami appearing as a white horizontal line in the distant horizon, gradually becoming bigger (bore-like), engulfing a jet skier and lifting two police boats.<ref>{{cite journal|last1=Yamazaki|first1=Fumio|last2=Matsuoka|first2=Masashi|last3=Warnitchai|first3=Pennung|last4=Polngam|first4=Supapis|last5=Ghosh|first5=Shubharoop|display-authors=1|title=Tsunami Reconnaissance Survey in Thailand Using Satellite Images and GPS|journal=Asian Journal of Geoinformatics|publisher=[[Chiba University]]|citeseerx=10.1.1.564.5976}}</ref> A maximum inundation of approximately {{cvt|2|km|abbr=out}} was measured, the inundated depths were {{cvt|4|-|7|m}} and there was evidence that the tsunami reached the third floor of a resort hotel. The tsunami in Khao Lak was bigger due to offshore coral reefs and shallow seafloor which caused the tsunami to pile-up. This was similar to eyewitness accounts of the tsunami at [[Banda Aceh]].

[[Khao Lak]] also experienced the largest tsunami run-up height outside of [[Sumatra]].<ref name="ReferenceB">{{cite web|url=http://www.tsunami.civil.tohoku.ac.jp/sumatra2004/C4.pdf|title=Chapter 4: Field Survey and Numerical Simulation on the 2004 Off-Sumatra Earthquake and Tsunami in Thailand|publisher=[[Tohoku University]]|access-date=10 October 2015|archive-date=15 February 2017|archive-url=https://web.archive.org/web/20170215154938/http://www.tsunami.civil.tohoku.ac.jp/sumatra2004/C4.pdf|url-status=live}}</ref>{{page needed|date=September 2018}} The highest-recorded tsunami run-up was measured {{cvt|19.6|m}} at Ban Thung Dap, on the south-west tip of [[Ko Phra Thong]] Island and the second-highest at {{cvt|15.8|m}} at Ban Nam Kim.<ref name="marine.tmd.go.th"/> Moreover, the largest death toll occurred at Khao Lak, with about 5,000 people killed.

In addition, the tsunami inflicted damage to the popular resort town of [[Ao Nang]] in Krabi Province. Video footage showed that the tsunami appeared as multiple white surfs violently lifting up yachts, boats and crashing onto beaches. Footage captured at [[Ko Lanta Yai|Koh Lanta]] showed a wall of water swamping the beach, while another video taken at another location showed a large [[surfing]] wave like tsunami approaching the shore, lifting up a yacht and flooding the beach. At Koh Sriboya, the tsunami advanced inland as a turbulent medium bore, while at Koh Phayam, [[Ranong Province]], the tsunami appeared as a wall of water.

At [[Phuket Province]], the island province's western beaches were struck by the tsunami. At [[Patong Beach]], a popular tourist destination, the tsunami first arrived as a small flood, which swept away cars and surprised people. About 10 minutes later, the sea receded for a while before the tsunami arrived again as a large wall of water looming over the skyline and flooding the coast. Another video from Kamala Beach showed the tsunami flooding the ground floor of a restaurant sweeping away an elderly couple. On [[Karon Beach]], Kamala Beach and [[Kata Beach]], the tsunami came in like a surging flood inland carrying people and cars. On some locations, a coastal road was built which was higher than the shore, protecting a hotel which was behind it. On the east coast of Phuket Island, the tsunami height was about 2 m. In one river mouth, many boats were damaged. The tsunami moved counter-clockwise around Phuket Island, as was the case at [[Okushiri Island]] in the [[1993 Okushiri earthquake|1993 Hokkaido earthquake]]. According to interviews, the second wave was the largest.<ref name="ReferenceB"/> The tsunami heights were {{cvt|5|-|6|m}} and the inundated depth was about {{cvt|2|m|ft}}. The tsunami surprised many tourists at Koh Racha Yai, where it flooded the resorts. About 250 people perished directly in the tsunami.

The [[Phi Phi Islands]] are a group of small islands that were affected by the tsunami. The north bay of Phi Phi Don Island opens to the north-west in the direction of the tsunami. The measured tsunami height on this beach was {{cvt|5.8|m}}. According to eyewitness accounts, the tsunami came from the north and south. The ground level was about 2 m above sea level, where there were many cottages and hotels. The south bay opens to the south-east and faces in the opposite direction from the tsunami. Furthermore, Phi Phi Le Island shields the port of Phi Phi Don Island. The measured tsunami height was {{cvt|4.6|m}} in the port.<ref name="ReferenceB"/> Amateur camcorder footage taken by Israeli tourists showed the tsunami advancing inland suddenly as a small flood, gradually becoming more powerful and engulfing the whole beach and resort, with the tsunami carrying a yacht out to sea.

Moreover, the tsunami was detected by scuba divers around offshore islands like the [[Similan Islands]] and the [[Surin Islands]]. The divers reported being caught in a violent, swirling current suddenly while underwater. Local camcorder footage showed the tsunami surging inland and flooding camping equipment at the Similan Islands while the tsunami caught tourists unaware at the Surin Islands, and dragging them out towards the sea.

===India===
[[File:Tree stumps and debris remain on Karaikal beach after the 2004 tsunami.jpg|thumb|upright=1.1|Tree stumps and debris remain on Karaikal beach several years after the 2004 tsunami]]
The tsunami reached the states of [[Andhra Pradesh]] and [[Tamil Nadu]] along the southeastern coastline of the Indian mainland about two hours after the earthquake. At the same time, it arrived in the state of [[Kerala]], on the southwestern coast. There were two to five tsunamis that coincided with the local high tide in some areas.<ref name="mapsofindia.com">{{cite web|url=http://www.mapsofindia.com/maps/tsunami-in-india/tsunami-affected-area-india.html|title=Tsunami Affected Areas in India 2004|publisher=Maps of India|access-date=17 October 2015|archive-date=7 December 2015|archive-url=https://web.archive.org/web/20151207184649/http://www.mapsofindia.com/maps/tsunami-in-india/tsunami-affected-area-india.html|url-status=live}}</ref><ref>{{cite web|url=http://academic.evergreen.edu/g/grossmaz/cramerbd/%3E|title=Zoltán Grossman – Member of the Faculty in Geography & Native Studies|publisher=The Evergreen State College|location=Olympia, Washington|access-date=9 June 2016|archive-date=30 December 2021|archive-url=https://web.archive.org/web/20211230015452/https://sites.evergreen.edu/zoltan/|url-status=live}}</ref><ref name="books.google.com.my">{{cite book|url=https://books.google.com/books?id=fICXQSPJwx8C|title=Natural and Anthropogenic Disasters: Vulnerability, Preparedness and Mitigation|first=M.K.|last=Jha|date=2010|publisher=Springer Science & Business Media|isbn=9789048124985|access-date=9 June 2016|archive-date=3 December 2016|archive-url=https://web.archive.org/web/20161203153914/https://books.google.com/books?id=fICXQSPJwx8C|url-status=live}}</ref><ref name="iitk.ac.in">{{cite journal|url=http://www.iitk.ac.in/nicee/RP/2006_Effect_EQSpectra.pdf|title=Effects of the December 2004 Indian Ocean Tsunami on the Indian Mainland|first1=Alpa|last1=Sheth|first2=Snigdha|last2=Sanyal|first3=Arvind|last3=Jaiswal|first4=Prathibha|last4=Gandhi|display-authors=1|journal=Earthquake Spectra|volume=22|issue=S3|pages=S435–S473|date=June 2006|doi=10.1193/1.2208562|bibcode=2006EarSp..22..435S|s2cid=110385551|access-date=4 August 2016|archive-date=3 March 2016|archive-url=https://web.archive.org/web/20160303170856/http://www.iitk.ac.in/nicee/RP/2006_Effect_EQSpectra.pdf|url-status=live}}</ref>

The tsunami runup height measured in mainland India by Ministry of Home Affairs includes:<ref name="iitk.ac.in"/>
* {{cvt|3.4|m}} at Kerala, inundation distance of {{cvt|0.5|-|1.5|km}} with {{cvt|250|km}} of coastline affected
* {{cvt|4.5|m}} at the southern coastline of Tamil Nadu, inundation distance of {{cvt|0.2|-|2|km}} with {{cvt|100|km}} of coastline affected
* {{cvt|5|m}} at the eastern coastline of Tamil Nadu facing tsunami source, inundation distance of {{cvt|0.4|-|1.5|km}} with {{cvt|800|km}} of coastline affected
* {{cvt|4|m}} at [[Puducherry (city)|Pondicherry]], inundation distance of {{cvt|0.2|-|2|km}} with {{cvt|25|km}} of coastline affected
* {{cvt|2.2|m|ft}} at Andhra Pradesh, inundation distance of {{cvt|0.2|-|1|km}} with {{cvt|985|km}} of coastline affected

Along the coast of Tamil Nadu, the {{cvt|13|km}} [[Marina Beach]] in [[Chennai]] was battered by the tsunami which swept across the beach taking morning walkers unaware. Amateur video recorded at a resort beach showed the tsunami arriving as a large wall of water as it approached the coast and flooding it as it advanced inland. Besides that, a {{cvt|10|m}} black muddy tsunami ravaged the city of [[Karaikal]], where 492 people died. The city of Pondicherry, protected by seawalls was relatively unscathed. Local video recorded that before the arrival of the tsunami, people had swarmed the beach to investigate fish that had been stranded on the sand. Furthermore, at the coastal town of [[Kanyakumari]], the seabed was exposed briefly before a large wall of water can be seen on the horizon and subsequently flooding the town. Other footage showed the tsunami dramatically crashed into the [[Vivekananda Rock Memorial]]. The worst affected area in Tamil Nadu was [[Nagapattinam district]], with 6,051 fatalities caused by a {{cvt|5|m}} tsunami, followed by [[Cuddalore district]], with many villages destroyed. Most of the people killed were members of the fishing community.<ref name="iitk.ac.in"/> [[Velankanni]], a coastal town with a Catholic [[Basilica of Our Lady of Good Health|Basilica]] and a popular pilgrimage destination was also one of the worst hit by the tsunami that struck at around 9.30 am on that Sunday, when pilgrims who were mostly from Kerala among others were inside the church attending the [[Malayalam]] [[Mass (Catholic Church)|Mass]]. The rising sea water did not enter the shrine, but the receding waters swept away hundreds of pilgrims who were on the beach.<ref name="RED2">{{cite news|date=28 December 2004|title=Velankanni: Death in the churchyard|work=[[Rediff.com]]|url=http://www.rediff.com/news/2004/dec/28iype1.htm|access-date=21 August 2014|archive-date=24 September 2015|archive-url=https://web.archive.org/web/20150924155257/http://www.rediff.com/news/2004/dec/28iype1.htm|url-status=live}}</ref> The shrine's compound, nearby villages, hundreds of shops, homes and pilgrims were washed away into the sea. About 600 pilgrims died.<ref name="BBC2">{{cite news|date=27 March 2005|title=Tsunami sufferers question faith|publisher=BBC News|url=http://news.bbc.co.uk/2/hi/south_asia/4382689.stm|access-date=21 August 2014|archive-date=2 November 2014|archive-url=https://web.archive.org/web/20141102203253/http://news.bbc.co.uk/2/hi/south_asia/4382689.stm|url-status=live}}</ref> Rescue teams extricated more than 400 bodies from the sand and rocks in the vicinity and large number of unidentified bodies were buried in mass graves.

Kerala experienced tsunami-related damage in three southern densely populated districts, [[Ernakulam]], [[Alappuzha]], and [[Kollam]], due to diffraction of the waves around Sri Lanka. The southernmost district of [[Thiruvananthapuram]], however, escaped damage, possibly due to the wide turn of the diffracted waves at the peninsular tip. Major damage occurred in two narrow strips of land bound on the west by the [[Arabian Sea]] and on the east by the [[Kerala backwaters]]. The waves receded before the first tsunami with the highest fatality reported from the densely populated [[Alappad]] panchayat (including the villages of [[Cheriazheekkal]] and [[Azheekal]]) at Kollam district, caused by a {{cvt|4|m}} tsunami.<ref name="iitk.ac.in"/>

[[File:Chennai damage 1.jpg|thumb|upright=1.1|A Toyota Corolla deposited on top of a fence and various pieces of debris in [[Chennai]]]]

Many villages in Andhra Pradesh were destroyed. In the [[Krishna District]], the tsunami created havoc in [[Manginapudi]] and on [[Machalipattanam]] Beach. The most affected was [[Prakasam District]], recording 35 deaths, with maximum damage at [[Singarayakonda]]. Given the enormous power of the tsunami, the fishing industry suffered the greatest. Moreover, the cost of damage in the transport sector was reported in the tens of thousands.<ref name="iitk.ac.in"/>

The tsunami run-up was only {{cvt|1.6|m|ft}} in areas of Tamil Nadu shielded by the island of Sri Lanka but was {{cvt|4|-|5|m}} in coastal districts such as [[Nagapattinam]] in Tamil Nadu directly across from [[Sumatra]]. On the western coast, the runup elevations were {{cvt|4.5|m}} at [[Kanyakumari District]] in Tamil Nadu and {{cvt|3.4|m}} each at Kollam and Ernakulam districts in Kerala. The time between the waves ranged from about 15 minutes to 90 minutes.<ref name="mapsofindia.com"/><ref name="books.google.com.my"/><ref name="academic.evergreen.edu">{{cite web|url=http://academic.evergreen.edu/g/grossmaz/cramerbd/|archive-url=https://web.archive.org/web/20080208140737/http://academic.evergreen.edu/g/grossmaz/cramerbd/|archive-date=8 February 2008|title=Tsunami's Impact on India|first=Brandon|last=Cramer|publisher=[[Evergreen College]]|access-date=22 December 2018}}</ref> The tsunami varied in height from {{Cvt|2|m|ft}} to {{Cvt|10|m|ft}} based on survivors' accounts. The tsunami travelled {{cvt|2.5|km}} at its maximum inland at Karaikal, [[Puducherry (union territory)|Puducherry]].<ref name="iitk.ac.in"/> The [[inundation]] distance varied between {{cvt|1006|-|500|m}} in most areas, except at river mouths, where it was more than {{cvt|1|km}}. Areas with dense coconut groves or mangroves had much smaller inundation distances, and those with river mouths or backwaters saw larger inundation distances.{{citation needed|date=June 2016}} Presence of seawalls at the Kerala and Tamil Nadu coasts reduced the impact of the waves. However, when the seawalls were made of loose stones, the stones were displaced and carried a few metres inland.<ref name="mapsofindia.com"/><ref name="books.google.com.my"/><ref name="academic.evergreen.edu"/>

====Andaman and Nicobar Islands====

Due to close proximity to the earthquake, the tsunami took just minutes to devastate the [[Andaman and Nicobar Islands]]. The Andaman Islands were moderately affected while the island of [[Little Andaman]] and the [[Nicobar Islands]] were severely affected by the tsunami.

In [[South Andaman Island]], based on local eyewitnesses, there were three tsunami waves, with the third being the most destructive. Flooding occurred at the coast and low-lying areas inland, which were connected to open sea through creeks. Inundation was observed, along the east coast of South Andaman Island, restricted to [[Chidiyatapu]], [[Burmanallah]], [[Kodiaghat]], [[Beadnabad]], [[Corbyn's Cove]] and Marina Park/[[Aberdeen Jetty]] areas. Several near-shore establishments and numerous infrastructures such as seawalls and a 20 MW diesel-generated power plant at Bamboo Flat were destroyed.<ref name=Ghosh>T. Ghosh, P. Jana, T.S. Giritharan, S. Bardhan, S.R. Basir, A.K. Ghosh Roy. (2007). Tsunami survey in Andaman and Nicobar group of Islands. Geological Survey of India Special Publication no. 89. 165–184.</ref> At [[Port Blair]], the water receded before the first wave, and the third wave was the tallest and caused the most damage.

Results of the tsunami survey in South Andaman along Chiriyatapu, Corbyn's Cove and Wandoor beaches:{{citation needed|date=September 2018}}
* {{cvt|5|m}} in maximum tsunami height with a run-up of {{cvt|4.24|m}} at Chiriyatapu Beach
* {{cvt|5.5|m}} in maximum tsunami height and run-up at Corbyn's Cove Beach
* {{cvt|6.6|m}} in maximum tsunami height and run-up of {{cvt|4.63|m}} at Wandoor Beach

Meanwhile, in the Little Andaman, tsunami waves impinged on the eastern shore about 25 to 30 minutes after the earthquake in a four-wave cycle of which the fourth tsunami was the most devastating with a wave height of about {{cvt|10|m}}. The tsunami destroyed settlements at [[Hut Bay]] within a range of {{cvt|1|km}} from the seashore. Run up level up to {{cvt|3.8|m}} have been measured.<ref name=Ghosh/>

In [[Malacca, Car Nicobar|Malacca]], located on the island of [[Car Nicobar]], there were three tsunami waves. The sea was observed to rise suddenly before the onset of the first wave. The first wave came 5 minutes after the earthquake, preceded by a recession of the sea up to {{cvt|600|-|700|m}}.{{citation needed|date=September 2018}}. The second and third waves came in 10 minutes intervals after the first wave. The third wave was the strongest, with a maximum tsunami wave height of {{cvt|11|m}}. Waves nearly three stories high devastated the [[Indian Air Force]] base, located just south of Malacca. The maximum tsunami wave height of {{cvt|11|m}}.{{citation needed|date=September 2018}} Inundation limit was found to be up to {{cvt|1.25|km}} inland. The impact of the waves was so severe that four oil tankers were thrown almost {{cvt|800|m}} from the seashore near Malacca to the Air force colony main gate.<ref name=Ghosh/> In [[Chuckchucha]] and [[Lapati]], the tsunami arrived in a three-wave cycle with a maximum tsunami wave height of {{cvt|12|m}}.

In [[Campbell Bay (Great Nicobar)|Campbell Bay]] of [[Great Nicobar]] Island, the tsunami waves hit the area three times with an inundation limit of {{cvt|250|-|500|m}}. A rise in sea level was observed before the first wave came within 5 minutes of the earthquake. The second and third waves came in 10-minute intervals after the first. The second wave was the strongest. The tsunami waves wreaked havoc in the densely populated Jogindar Nagar area, situated {{cvt|13|km}} south of Campbell Bay.{{citation needed|date=September 2018}} According to local accounts,{{attribution needed|date=September 2018}} tsunami waves attacked the area three times. The first wave came five minutes after the mainshock (0629 hrs.) with a marginal drop in sea level. The second wave came 10 minutes after the first one with a maximum height of {{cvt|4.8|m}} to 8&nbsp;m (26&nbsp;ft) and caused the major destruction. The third wave came within 15 minutes after the second with lower wave height. The maximum inundation limit due to tsunami water was about {{cvt|500|m}}.<ref name=Ghosh/>

The worst affected island in the Andaman and Nicobar chain is [[Katchall Island]], with 303 people confirmed dead and 4,354 missing out of a total population of 5,312.<ref>{{cite web|url=http://iset.org.in/pdf/souvenir%20&%20abstract%20volume/37-41.pdf|title=Damage to Andaman & Nicobar Islands due to Earthquake and Tsunami of Dec. 26, 2004|last1=Paul|first1=D.K.|last2=Singh|first2=Yogendra|last3=Dubey|first3=R.N.|publisher=Department of Earthquake Engineering, IIT Roorkee|access-date=20 December 2016|archive-url=https://web.archive.org/web/20181001202201/http://iset.org.in/pdf/souvenir%20%26%20abstract%20volume/37-41.pdf|archive-date=1 October 2018|url-status=dead}}</ref><ref name="andamanconnections.com">{{cite web|url=http://andamanconnections.com/andaman_tsunami.html|title=Tsunami in Andaman & Nicobar Islands|work=Andamanconnections.com|access-date=20 December 2016|archive-url=https://web.archive.org/web/20161216080235/http://andamanconnections.com/andaman_tsunami.html|archive-date=16 December 2016|url-status=dead}}</ref><ref name="istructe.org">{{cite book|last1=Pomonis|first1=Antonios|url=https://www.istructe.org/downloads/resources-centre/technical-topic-area/eefit/eefit-reports/indian-ccean-tsunami.pdf|title=The Indian Ocean Tsunami of 26 December 2004: Mission Findings in Sri Lanka and Thailand|last2=Rossetto|first2=Tiziana|last3=Peiris|first3=Navin|last4=Wilkinson|first4=Sean|last5=Del Re|first5=Domenico|last6=Koo|first6=Raymond|last7=Manlapig|first7=Raul|last8=Gallocher|first8=Stewart|date=February 2006|publisher=Earthquake Engineering Field Investigation Team, Institution of Structural Engineers|isbn=978-0-901297-41-9|place=London|author-link2=Tiziana Rossetto|access-date=25 September 2016|archive-date=27 September 2016|archive-url=https://web.archive.org/web/20160927005453/https://www.istructe.org/downloads/resources-centre/technical-topic-area/eefit/eefit-reports/indian-ccean-tsunami.pdf|url-status=live}}</ref> The significant shielding of Port Blair and Campbell Bay by steep mountainous outcrops contributed to the relatively low wave heights at these locations, whereas the open terrain along the eastern coast at Malacca and [[Hut Bay]] contributed to the great height of the tsunami waves.<ref name="andamanconnections.com"/><ref>{{cite web|url=http://www.nicee.org/SumatraEQ_India_IITK_QuickReport.pdf|title=Quick Report on the Study of the 2004 Sumatra Earthquake and Tsunami Effects|publisher=Department of Civil Engineering, Indian Institute of Technology Kanpur|access-date=21 December 2016|archive-date=10 October 2017|archive-url=https://web.archive.org/web/20171010152754/http://www.nicee.org/SumatraEQ_India_IITK_QuickReport.pdf|url-status=live}}</ref>

Reports of tsunami wave height:<ref>{{cite web|url=https://www.eeri.org/lfe/pdf/india_tsunami_eeri_report.pdf|title=The Great Sumatra Earthquake and Indian Ocean Tsunami of December 26, 2004: The Effects in Mainland India and in the Andaman-Nicobar Islands|work=EERI Special Earthquake Report|date=April 2005|access-date=21 December 2016|archive-date=10 October 2016|archive-url=https://web.archive.org/web/20161010004407/https://www.eeri.org/lfe/pdf/india_tsunami_eeri_report.pdf|url-status=live}}</ref><ref>{{cite journal|first1=M. V.|last1=Ramanamurthy|first2=S.|last2=Sundaramoorthy|first3=Y.|last3=Pari|first4=V. Ranga|last4=Rao|first5=P.|last5=Mishra|first6=M.|last6=Bhat|first7=Tune|last7=Usha|first8=R.|last8=Venkatesan|first9=B. R.|last9=Subramanian|display-authors=1|url=http://www.iisc.ernet.in/currsci/jun102005/1736.pdf|pages=1736–1740|journal=[[Current Science]]|volume=88|issue=11|date=10 June 2005|title=Inundation of sea water in Andaman and Nicobar Islands and parts of Tamil Nadu coast during 2004 Sumatra tsunami|access-date=25 September 2016|archive-date=27 September 2016|archive-url=https://web.archive.org/web/20160927083425/http://www.iisc.ernet.in/currsci/jun102005/1736.pdf|url-status=live}}</ref>

* {{cvt|1.5|m}} at [[Diglipur]] and [[Rangat]] at North Andaman Island
* {{cvt|8|m}} high at Campbell Bay on [[Great Nicobar Island]]
* {{cvt|10|-|12|m}} high at Malacca (in Car Nicobar Island) and at Hut Bay on [[Little Andaman Island]]
* {{cvt|3|m}} high at Port Blair on South Andaman Island

===Maldives===
The tsunami severely affected the [[Maldives]] at a distance of {{cvt|2500|km}} from the epicentre. Similar to Sri Lanka, survivors reported three waves with the second wave being the most powerful.<ref name="faculty.vassar.edu"/> Being rich in coral reefs, the Maldives provides an opportunity for scientists to assess the impact of a tsunami on coral atolls. The significantly lower tsunami impact on the Maldives compared to Sri Lanka is mostly due to the topography and [[bathymetry]] of the atoll chain with offshore coral reefs, deep channels separating individual atolls and its arrival within low tide which decreased the power of the tsunami.<ref>{{cite journal|last1=Fritz|first1=Hermann M.|last2=Synolakis|first2=Costas E.|last3=McAdoo|first3=Brian G.|title=Maldives Field Survey after the December 2004 Indian Ocean Tsunami|journal=Earthquake Spectra|date=June 2006|volume=22|issue=3_suppl|pages=137–154|doi=10.1193/1.2201973|bibcode=2006EarSp..22..137F }}</ref> After the tsunami, there was some concern that the country might be submerged entirely and become uninhabitable. However, this was proven untrue.

The highest tsunami wave measured was {{cvt|4|m}} at [[Vilufushi (Thaa Atoll)|Vilufushi Island]]. The tsunami arrived approximately two hours after the earthquake. The greatest tsunami inundation occurred at [[North Male Atoll]], [[Male Island]] at {{cvt|250|m}} along the streets.<ref name="faculty.vassar.edu">{{cite journal|last1=Liu|first1=Philip L.-F.|last2=Lynett|first2=Patrick|last3=Fernando|first3=Harindra|last4=Jaffe|first4=Bruce E.|last5=Fritz|first5=Hermann|last6=Higman|first6=Bretwood|last7=Morton|first7=Robert|last8=Goff|first8=James|last9=Synolakis|first9=Costas|title=Observations by the International Tsunami Survey Team in Sri Lanka|journal=Science|date=10 June 2005|volume=308|issue=5728|pages=1595|doi=10.1126/science.1110730|pmid=15947179 |bibcode=2005Sci...308.1595L }}</ref>

Local footage recorded showed the tsunami flooding the streets up to knee level in town, while another video taken at the beach showed the tsunami slowly flooding and gradually surging inland.

The Maldives tsunami wave analysis:<ref name="faculty.vassar.edu" />
* {{cvt|1.3|-|2.4|m}} at North Male Atoll, Male Island
* {{cvt|2|m}} at North Male Atoll, [[Huhule Island]]
* {{cvt|1.7|-|2.8|m}} at [[South Male Atoll]], [[Embudhu Finothu]]
* {{cvt|2.5|-|3.3|m}} at [[Laamu Atoll]], [[Fonadhoo Island]]
* {{cvt|2.2|-|2.9|m}} at Laamu Atoll, [[Gan Island]]
* {{cvt|2.3|-|3|m}} at North Male Atoll, [[Dhiffushi Island]]
* {{cvt|2.2|-|2.4|m}} at North Male Atoll, [[Huraa Island]]
* more than {{cvt|1.5|m}} at North Male Atoll, [[Kuda Huraa Island]]

===Myanmar===
In [[Myanmar]], the tsunami caused only moderate damage, which arrived between 2 and 5.5 hours after the earthquake. Although the country's western [[Andaman Sea]] coastline lies at the proximity of the rupture zone, there were smaller tsunamis than the neighbouring Thai coast, because the main tsunami source did not extend to the Andaman Islands. Another factor is that some coasts of [[Taninthayi Division]] were protected by the [[Myeik Archipelago]]. Based on scientific surveys from the [[Irrawaddy Delta]] through Taninthayi Division, it was revealed that tsunami heights along the Myanmar coast were between {{cvt|0.4|-|2.9|m}}. Eyewitnesses compared the tsunami with the "rainy-season high tide"; although at most locations, the tsunami height was similar or smaller than the "rainy-season high tide" level.<ref name="terrapub.co.jp">{{cite journal|url=https://www.terrapub.co.jp/journals/EPS/pdf/2006/5802/58020243.pdf|first1=Kenji|last1=Satake|first2=Than Tin|last2=Aung|first3=Yuki|last3=Sawai|first4=Yukinobu|last4=Okamura|display-authors=1|title=Tsunami heights and damage along the Myanmar coast from the December 2004 Sumatra-Andaman earthquake|journal=Earth Planets Space|volume=58|issue=2|pages=243–252|year=2006|access-date=22 December 2018|doi=10.1186/BF03353384|bibcode=2006EP&S...58..243S|s2cid=129597697|doi-access=free|archive-date=4 October 2018|archive-url=https://web.archive.org/web/20181004032411/https://www.terrapub.co.jp/journals/EPS/pdf/2006/5802/58020243.pdf|url-status=live}}</ref>

Tsunami survey heights:{{citation needed|date=September 2018}}
* {{cvt|0.6|-|2.3|m}} around the Irrawaddy delta
* {{cvt|0.9|-|2.9|m}} at [[Dawei]] area
* {{cvt|0.7|-|2.2|m}} around [[Myeik, Burma|Myeik]]
* {{cvt|0.4|-|2.6|m}} around [[Kawthaung]]

Interviews with residents indicate that they did not feel the earthquake in Taninthayi Division or the Irrawaddy Delta. The 71 casualties can be attributed to poor housing infrastructure and additionally, the fact that the coastal residents in the surveyed areas live on flat land along the coast, especially in the Irrawaddy Delta, and that there is no higher ground to which to evacuate. The tsunami heights from the earthquake were not more than {{cvt|3|m}} along the Myanmar coast, the amplitudes were slightly large off the Irrawaddy Delta, probably because the shallow delta caused a concentration in tsunami energy.<ref name="terrapub.co.jp"/>

===Somalia===
The tsunami travelled {{cvt|5000|km}} west across the open ocean before striking the East African country of [[Somalia]]. Around 289 fatalities were reported in the [[Horn of Africa]], drowned by four tsunami waves. The hardest-hit was a {{cvt|650|km}} stretch of coastline between [[Garacad]] ([[Mudug]] region) and [[Hafun]] ([[Bari, Somalia|Bari]] region), which forms part of [[Puntland]] province. Most of the victims were reported along the low-lying [[Ras Hafun|Xaafuun Peninsula]].<ref name="2004tsunami.ce.gatech.edu">{{cite journal|url=http://2004tsunami.ce.gatech.edu/publications/som_eqs_v22-iS3_106607eqs.pdf|title=Somalia Field Survey after the December 2004 Indian Ocean Tsunami|first1=Hermann M.|last1=Fritz|first2=Jose C.|last2=Borrero|doi=10.1193/1.2201972|journal=Earthquake Spectra|volume=22|issue=S3|pages=S219–S233|date=June 2006|bibcode=2006EarSp..22..219F|s2cid=220297402|access-date=22 December 2018|archive-date=24 February 2021|archive-url=https://web.archive.org/web/20210224013252/http://2004tsunami.ce.gatech.edu/publications/som_eqs_v22-iS3_106607eqs.pdf|url-status=live}}</ref> The Puntland coast in northern Somalia was by far the area hardest hit by the waves to the west of the Indian subcontinent. The waves arrived around noon local time.<ref name="2004tsunami.ce.gatech.edu"/>

Consequently, tsunami runup heights vary from {{cvt|5|m}} to {{cvt|9|m}} with inundation distances varying from {{cvt|44|m}} to {{cvt|704|m}}. The maximum runup height of almost {{cvt|9|m}} was recorded in [[Bayla|Bandarbeyla]]. An even higher runup point was measured on a cliff near the town of [[Eyl]], solely on an eyewitness account.

The highest death toll was in Hafun, with 19 dead and 160 people presumed missing out of its 5,000 inhabitants. This was the highest number of casualties in a single African town and the largest tsunami death toll in a single town to the west of the [[Indian subcontinent]]. Small drawbacks were observed before the third and most powerful tsunami wave flooded the town.<ref name="2004tsunami.ce.gatech.edu"/>

===Other locations===
[[File:Tanjungtokongwave.png|thumb|upright=1.1|Flooding in [[George Town, Penang|George Town]], Malaysia]]
The tsunami also reached Malaysia, mainly on the northern states such as [[Kedah]], Perak and [[Penang]] and on offshore islands such as [[Langkawi]] island. [[Peninsular Malaysia]] was shielded by the full force of the tsunami due to the protection offered by the island of Sumatra, which lies just off the western coast.<ref>{{Cite web|url=https://www.smh.com.au/world/asia/tsunami-death-toll-passes-283-000-20050128-gdkkw6.html|title=Tsunami death toll passes 283,000|date=28 January 2005|website=The Sydney Morning Herald|access-date=10 January 2020|archive-date=15 November 2019|archive-url=https://web.archive.org/web/20191115041926/https://www.smh.com.au/world/asia/tsunami-death-toll-passes-283-000-20050128-gdkkw6.html|url-status=live}}</ref>

Bangladesh escaped major damage and deaths because the water displaced by the [[strike-slip fault]] was relatively little on the northern section of the rupture zone, which ruptured slowly. In [[Yemen]], the tsunami killed two people with a maximum runup of {{cvt|2|m|ft}}.<ref>{{Cite web|url=http://itic.ioc-unesco.org/index.php?option=com_content&view=category&id=1136&Itemid=1136|title=International Tsunami Information Center – International Tsunami Information Center|website=itic.ioc-unesco.org|access-date=17 October 2015|archive-date=19 April 2016|archive-url=https://web.archive.org/web/20160419214841/http://itic.ioc-unesco.org/index.php?option=com_content&view=category&id=1136&Itemid=1136|url-status=live}}</ref>

The tsunami was detected in the southern parts of east Africa, where rough seas were reported, specifically on the eastern and southern coasts that face the Indian Ocean. A few other African countries also recorded fatalities; one in Kenya, three in [[Seychelles]], ten in Tanzania, and South Africa, where two were killed as a direct result of the tsunami—the furthest from the epicentre.<ref>{{cite web|url=https://www.researchgate.net/publication/241273975|title=Field Surveys of 2004 Indian Ocean Tsunami From Sumatra to East Africa|first1=Hermann M.|last1=Fritz|first2=Jose C.|last2=Borrero|first3=Costas E.|last3=Synolakis|first4=Emile A.|last4=Okal|date=1 January 2006|access-date=29 January 2018|archive-date=30 December 2021|archive-url=https://web.archive.org/web/20211230015407/https://www.researchgate.net/publication/241273975_FIELD_SURVEYS_OF_2004_INDIAN_OCEAN_TSUNAMI_FROM_SUMATRA_TO_EAST_AFRICA|url-status=live}}</ref><ref>{{cite web|url=https://smartech.gatech.edu/bitstream/handle/1853/42307/103954_Unesco_Yemen_Tsunami_FzOk3.pdf?sequence=1|title=Unesco Yemen Tsunami|work=smartech.gatech.edu|access-date=13 November 2017|archive-date=10 October 2017|archive-url=https://web.archive.org/web/20171010152811/https://smartech.gatech.edu/bitstream/handle/1853/42307/103954_Unesco_Yemen_Tsunami_FzOk3.pdf?sequence=1|url-status=live}}</ref>

Tidal surges also occurred along the [[Western Australian]] coast that lasted for several hours, resulting in boats losing their moorings and two people needing to be rescued.<ref>{{Cite web|url=https://www.smh.com.au/world/asia/wa-feels-the-tsunamis-ripples-20041229-gdke6z.html|title=WA feels the tsunami's ripples|date=28 December 2004|website=The Sydney Morning Herald|access-date=10 January 2020|archive-date=22 September 2019|archive-url=https://web.archive.org/web/20190922000416/https://www.smh.com.au/world/asia/wa-feels-the-tsunamis-ripples-20041229-gdke6z.html|url-status=live}}</ref>

==Impact==
===Countries affected===
{{main|Countries affected by the 2004 Indian Ocean earthquake and tsunami}}

[[File:2004 Tsunami casualties and damage.png|thumb|upright=1.5|{{legend|red|severe damage and loss of life}}{{legend|orange|moderate damage and some loss of life}}{{legend|yellow|minor damage and no loss of life}}{{legend|dodgerblue|loss of citizens abroad}}]]
According to the final report of the [[Tsunami Evaluation Coalition]], a total of 227,898 people died.<ref name="auto"/> Another common total, as given by the UN Office of the Special Envoy for Tsunami Recovery, is 229,866 dead.<ref name="UN Special Envoy">{{Cite web|work=UN Office of the Special Envoy for Tsunami Recovery|title=The Human Toll|url=http://www.tsunamispecialenvoy.org/country/humantoll.asp|date=January 2006|archive-url=https://web.archive.org/web/20060423184048/http://www.tsunamispecialenvoy.org/country/humantoll.asp|archive-date=23 April 2006}}</ref> Measured in lives lost, this is one of the ten [[Lists of earthquakes#Deadliest earthquakes|worst earthquakes in recorded history]], as well as the single worst tsunami in history. Indonesia was the worst affected area, with most death toll estimates at around 170,000.<ref>{{cite web|url=http://www.islamicreliefusa.org/home?aspxerrorpath=/404.aspx|title=Home|publisher=Islamic Relief USA|access-date=12 August 2010|archive-url=https://web.archive.org/web/20110119163003/http://www.islamicreliefusa.org/home?aspxerrorpath=/404.aspx|archive-date=19 January 2011|url-status=live}}</ref> The death toll for Indonesia alone may be as high as 172,761 lives.<ref>{{Cite journal|last1=Parwanto|first1=Novia Budi|last2=Oyama|first2=Tatsuo|year=2014|title=A statistical analysis and comparison of historical earthquake and tsunami disasters in Japan and Indonesia|journal=International Journal of Disaster Risk Reduction|volume=7|pages=122–141|doi=10.1016/j.ijdrr.2013.10.003|bibcode=2014IJDRR...7..122P|issn=2212-4209}}</ref> An initial report by [[Siti Fadilah Supari]], the Indonesian Minister of Health at the time, estimated the death total to be as high as 220,000 in Indonesia alone, giving a total of 280,000 fatalities.<ref name=BBC280>{{cite news|url=http://news.bbc.co.uk/1/hi/world/asia-pacific/4204385.stm|title=Indonesia quake toll jumps again|publisher=BBC News|date=25 January 2005|access-date=24 December 2012|archive-date=21 August 2021|archive-url=https://web.archive.org/web/20210821153214/http://news.bbc.co.uk/2/hi/asia-pacific/4204385.stm|url-status=live}}</ref> However, the estimated number of dead and missing in Indonesia were later reduced by over 50,000. In their report, the Tsunami Evaluation Coalition stated, "It should be remembered that all such data are subject to error, as data on missing persons especially are not always as good as one might wish".<ref>{{Cite book|last1=Telford|first1=John|url=https://cdn.sida.se/publications/files/sida61330en-joint-evaluation-of-the-international-response-to-the-indian-ocean-tsunami.pdf|title=Joint Evaluation of the International Response to the Indian Ocean Tsunami: Synthesis Report|last2=Cosgrave|first2=John|publisher=[[Tsunami Evaluation Coalition]]|year=2006|isbn=0-85003-807-3|location=London|pages=159}}</ref> A much higher number of deaths has been suggested for Myanmar based on reports from Thailand.<ref name="AsiaNews-Myanmar"/>

The tsunami caused severe damage and deaths as far as the east coast of Africa, with the furthest recorded fatality directly attributed to the tsunami at [[Rooi-Els, Western Cape|Rooi-Els]], close to [[Cape Town]], {{cvt|8000|km}} from the epicentre.<ref>{{Cite web|title=Hundreds of thousands of people killed as tsunamis devastate large swathes of South and Southeast Asia, coming as far as South Africa |url=https://www.sahistory.org.za/dated-event/hundreds-thousands-people-killed-tsunamis-devastate-large-swathes-south-and-southeast|access-date=15 November 2022|website=South African History Online|archive-date=15 November 2022|archive-url=https://web.archive.org/web/20221115221227/https://www.sahistory.org.za/dated-event/hundreds-thousands-people-killed-tsunamis-devastate-large-swathes-south-and-southeast|url-status=live}}</ref>

Relief agencies reported that one third of the dead appeared to be children. This was a result of the high proportion of children in the populations of many of the affected regions and because children were the least able to resist being overcome by the surging waters. [[Oxfam]] went on to report that as many as four times more women than men were killed in some regions because they were waiting on the beach for the fishers to return and looking after their children in the houses.<ref>{{cite news|url=http://news.bbc.co.uk/1/hi/world/asia-pacific/4383573.stm|title=Most tsunami dead female – Oxfam|publisher=BBC News|date=26 March 2005|access-date=24 December 2012|archive-date=26 July 2008|archive-url=https://web.archive.org/web/20080726142516/http://news.bbc.co.uk/1/hi/world/asia-pacific/4383573.stm|url-status=live}}</ref>

States of emergency were declared in Sri Lanka, Indonesia, and the Maldives. The United Nations estimated at the outset that the relief operation would be the costliest in human history.{{citation needed|date=September 2018}} Then-[[UN Secretary-General]] [[Kofi Annan]] stated that reconstruction would probably take between five and ten years. Governments and non-governmental organizations feared that the final death toll might double as a result of diseases, prompting a massive [[humanitarian response to the 2004 Indian Ocean earthquake|humanitarian response]].{{citation needed|date=September 2018}}

In addition to a large number of local residents, up to 9,000 foreign tourists (mostly Europeans) enjoying the peak holiday travel season were among the dead or missing, especially people from the [[Nordic countries]].<ref name="Onnettomuustutkintakeskus">{{cite web|title=A2/2004Y Aasian luonnonkatastrofi 26.12.2004|url=https://turvallisuustutkinta.fi/fi/index/tutkintaselostukset/muutonnettomuudet/tutkintaselostuksetvuosittain/muutonnettomuudet2004/a22004yaasianluonnonkatastrofi26.12.2004.html|publisher=Onnettomuustutkintakeskus|language=fi|date=26 December 2004|access-date=26 December 2019|archive-date=25 July 2021|archive-url=https://web.archive.org/web/20210725132234/https://turvallisuustutkinta.fi/fi/index/tutkintaselostukset/muutonnettomuudet/tutkintaselostuksetvuosittain/muutonnettomuudet2004/a22004yaasianluonnonkatastrofi26.12.2004.html|url-status=live}}</ref> Sweden was the European country most severely affected both in absolute numbers, and by a wide margin when considered in relation to the country's population, with a death toll of 543. France was close behind with a death toll of 542 followed by Germany with 539 identified victims.

<!-- Please update the relevant sections of the article before updating this table. Please update totals as well. NB: This table refers only to countries directly affected by the tsunami, not to countries whose citizens were affected while overseas. -->
{|class="wikitable sortable plainrowheaders" width="100%" style="padding-left:2em;"
|-
!scope=col|Affected country{{ref label|a|a}}
!scope=col|Confirmed deaths
!scope=col|Estimated deaths{{ref label|b|b}}
!scope=col|Injured
!scope=col|Missing
!scope=col|Displaced
!scope=col class=unsortable|Ref
|-
|style=padding-left:1em;|{{flagdeco|Indonesia}} [[Effect of the 2004 Indian Ocean earthquake on Indonesia|Indonesia]]
|style=padding-left:1em;|{{nts|130,736}}
|style=padding-left:1em;|{{nts|167,540}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|37,063}}
|style=padding-left:1em;|{{nts|500,000}}+
|style=text-align:center;|<ref name="Meisl">{{cite journal|author1=Meisl, C.S.|author2=Safaie S.|author3=Elwood K.J.|author4=Gupta R.|author5=Kowsari R.|year=2006|title=Housing Reconstruction in Northern Sumatra after the December 2004 Great Sumatra Earthquake and Tsunami|journal=Earthquake Spectra|doi=10.1193/1.2201668|volume=22|issue=3_suppl|pages=777–802|bibcode=2006EarSp..22..777M|s2cid=110185015}}</ref>
|-
|style=padding-left:1em;|{{flagdeco|Sri Lanka}} [[Effect of the 2004 Indian Ocean earthquake on Sri Lanka|Sri Lanka]]
|style=padding-left:1em;|{{nts|35,322}}{{ref label|c|c}}
|style=padding-left:1em;|{{nts|35,322}}
|style=padding-left:1em;|{{nts|21,411}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|516,150}}
|style=text-align:center;|<ref name="wsws1">{{cite web|url=http://www.wsws.org/articles/2005/dec2005/sri2-d29.shtml|title=One year after the tsunami, Sri Lankan survivors still live in squalour|publisher=World Socialist Web Site|date=29 December 2005|access-date=24 December 2012|archive-date=23 November 2012|archive-url=https://web.archive.org/web/20121123063125/http://www.wsws.org/articles/2005/dec2005/sri2-d29.shtml|url-status=live}}</ref>
|-
|style=padding-left:1em;|{{flagdeco|India}} [[Effect of the 2004 Indian Ocean earthquake on India|India]]
<!--NOTE: For India, the only "Confirmed" death tolls are found at the official website: http://www.ndmindia.nic.in. *Everything else* is to be listed under "Estimated". This is a serious problem because some media publications have already presumed that all the missing people are dead. Others report with the terminology "killed or feared killed". That makes it an estimate. Let's just use the official figures under "Confirmed". The "Displaced" numbers here do not include people whose homes are intact, but who were 'moved to a safer place', as with the other countries in the table. -->
|style=padding-left:1em;|{{nts|12,405}}
|style=padding-left:1em;|{{nts|16,269}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|3,874}}
|style=padding-left:1em;|{{nts|647,599}}
|style=text-align:center;|<!-- Please add reference -->
|-
|style=padding-left:1em;|{{flagdeco|Thailand}} [[Effect of the 2004 Indian Ocean earthquake on Thailand|Thailand]]
|style=padding-left:1em;|{{nts|5,395}}{{ref label|d|d}}
|style=padding-left:1em;|{{nts|8,212}}
|style=padding-left:1em;|{{nts|8,457}}
|style=padding-left:1em;|{{nts|2,817}}
|style=padding-left:1em;|{{nts|7,000}}
|style=text-align:center;|<ref name="memorial">{{cite web|url=http://www.tsunamimemorial.or.th/information.htm|archive-url=https://web.archive.org/web/20070928063502/http://www.tsunamimemorial.or.th/information.htm|archive-date=28 September 2007|title=TsunamiMemorial.or.th|date=28 September 2007|access-date=24 December 2012}}</ref><ref name="Schwartz">{{cite journal|author1=Schwartz, D.|author2=Goldberg A.|author3=Ashenasi I.|author4=Nakash G.|author5=Leiba A.|author6=Levei Y.|author7=Bar-Dayan Y.|year=2006|title=Prehospital care of tsunami victims in Thailand: description and analysis|journal=Prehospital and Disaster Medicine|volume=21|issue=3|pages=204–210|pmid=16892886|doi=10.1017/S1049023X0000368X|s2cid=25251413}}</ref>
|-
|style=padding-left:1em;|{{flagdeco|Somalia}} [[Effect of the 2004 Indian Ocean earthquake on Somalia|Somalia]]
|style=padding-left:1em;|{{nts|78}}
|style=padding-left:1em;|{{nts|289}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|5,000}}
|style=text-align:center;|<ref>{{cite news|author=Martin Plaut|url=http://news.bbc.co.uk/2/hi/africa/4560246.stm|title=Tsunami: Somalia's slow recovery|publisher=BBC News|date=26 December 2005|access-date=24 December 2012|archive-date=1 December 2012|archive-url=https://web.archive.org/web/20121201090554/http://news.bbc.co.uk/2/hi/africa/4560246.stm|url-status=live}}</ref><ref>{{cite web|url=http://www.reliefweb.int/w/rwb.nsf/UNID/D39A0A882D6A7E9985256F82006A1158?OpenDocument|title=India, Indonesia, Maldives, Myanmar, Somalia, Thailand: Earthquake and Tsunami OCHA Situation Report No. 14|publisher=ReliefWeb|access-date=12 August 2010|archive-date=7 May 2008|archive-url=https://web.archive.org/web/20080507034200/http://www.reliefweb.int/w/rwb.nsf/UNID/D39A0A882D6A7E9985256F82006A1158?OpenDocument|url-status=live}}</ref>
|-
|style=padding-left:1em;|{{flagdeco|Myanmar|1974}} [[Effect of the 2004 Indian Ocean earthquake on Myanmar|Myanmar]]
|style=padding-left:1em;|{{nts|61}}
|style=padding-left:1em;|{{nts|400}}–600
|style=padding-left:1em;|{{nts|45}}
|style=padding-left:1em;|{{nts|200}}
|style=padding-left:1em;|{{nts|3,200}}
|style=text-align:center;|<ref name="AsiaNews-Myanmar"/><ref>{{cite news|url=http://news.bbc.co.uk/2/hi/asia-pacific/4145489.stm|title=Asia-Pacific &#124; 'Hundreds feared dead' in Burma|publisher=BBC News|date=4 January 2005|access-date=24 December 2012|archive-date=4 November 2012|archive-url=https://web.archive.org/web/20121104164106/http://news.bbc.co.uk/2/hi/asia-pacific/4145489.stm|url-status=live}}</ref>
|-
|style=padding-left:1em;|{{flagdeco|Maldives}} [[Effect of the 2004 Indian Ocean earthquake on the Maldives|Maldives]]
|style=padding-left:1em;|{{nts|82}}
|style=padding-left:1em;|{{nts|108}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|26}}
|style=padding-left:1em;|{{nts|15,000}}+
|style=text-align:center;|<ref>{{cite web|url=http://www.tsunamimaldives.mv/?action=situationAssesment|archive-url=https://web.archive.org/web/20090617182704/http://www.tsunamimaldives.mv/?action=situationAssesment|archive-date=17 June 2009|title=TsunamiMaldives.mv|access-date=24 December 2012}}</ref><ref name="UNICEF_Maldives2006">{{cite web|url=http://www.unicef.org/evaldatabase/files/UNICEF_Tsunami_Maldives_2006report.pdf|title=The 2004 Indian Ocean Tsunami Disaster: Evaluation of UNICEF's response (emergency and recovery phase). Maldives Report|work=UNICEF|date=May 2006|page=i|access-date=26 June 2011|archive-date=18 January 2012|archive-url=https://web.archive.org/web/20120118182452/http://www.unicef.org/evaldatabase/files/UNICEF_Tsunami_Maldives_2006report.pdf|url-status=dead}}</ref>
|-
|style=padding-left:1em;|{{flagdeco|Malaysia}} [[Effect of the 2004 Indian Ocean earthquake on Malaysia|Malaysia]]
|style=padding-left:1em;|{{nts|68}}
|style=padding-left:1em;|{{nts|75}}
|style=padding-left:1em;|{{nts|299}}
|style=padding-left:1em;|{{nts|6}}
|style=padding-left:1em;|{{nts|5000}}+
|style=text-align:center;|<ref>{{cite web|author=english@peopledaily.com.cn|url=http://english.people.com.cn/200501/13/eng20050113_170555.html|title=Death toll in Asian tsunami disaster tops 159,000|work=People's Daily|date=13 January 2005|access-date=12 August 2010|archive-date=9 June 2011|archive-url=https://web.archive.org/web/20110609220247/http://english.people.com.cn/200501/13/eng20050113_170555.html|url-status=live}}</ref><ref>{{cite web|url=http://www.channelnewsasia.com/killerwaves|archive-url=https://web.archive.org/web/20121023160459/http://www.channelnewsasia.com/killerwaves|archive-date=23 October 2012|title=Killer Waves|publisher=Channel NewsAsia|access-date=24 December 2012}}</ref>
|-
|style=padding-left:1em;|{{flagdeco|Tanzania}} [[Countries affected by the 2004 Indian Ocean earthquake#Countries suffering some casualties and damage|Tanzania]]
|style=padding-left:1em;|{{nts|10}}
|style=padding-left:1em;|{{nts|13}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|3}}
|style=padding-left:1em;|{{nts|}}
|style=text-align:center;|<ref>{{cite web|url=http://www.abc.net.au/news/newsitems/200501/s1275702.htm|title=Asian tsunami death toll passes 144,000|publisher=ABC|location=Australia|date=3 January 2005|access-date=12 August 2010|archive-url=https://web.archive.org/web/20090617042814/http://www.abc.net.au/news/newsitems/200501/s1275702.htm|archive-date=17 June 2009|url-status=dead}}</ref>
|-
|style=padding-left:1em;|{{flagdeco|Seychelles}} [[Countries affected by the 2004 Indian Ocean earthquake#Countries suffering some casualties and damage|Seychelles]]
|style=padding-left:1em;|{{nts|3}}
|style=padding-left:1em;|{{nts|3}}
|style=padding-left:1em;|{{nts|57}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|200}}
|style=text-align:center;|<ref name="rw">{{cite web|url=http://www.reliefweb.int/rw/RWB.NSF/db900SID/KHII-6KH4KY?OpenDocument|title=The Seychelles raises its voice|date=4 November 2005|access-date=12 August 2010|archive-date=6 May 2008|archive-url=https://web.archive.org/web/20080506125422/http://www.reliefweb.int/rw/RWB.NSF/db900SID/KHII-6KH4KY?OpenDocument|url-status=live}}</ref><ref>{{cite web|url=http://www.alnap.org/tec/pdf/TEC_initial_report_20051223_finalversion.pdf|title=Tsunami Evaluation Coalition: Initial Findings|access-date=12 August 2010|archive-url=https://web.archive.org/web/20060324222422/http://www.alnap.org/tec/pdf/TEC_initial_report_20051223_finalversion.pdf|archive-date=24 March 2006}}</ref>
|-
|style=padding-left:1em;|{{flagdeco|Bangladesh}} [[Countries affected by the 2004 Indian Ocean earthquake#Countries suffering some casualties and damage|Bangladesh]]
|style=padding-left:1em;|{{nts|2}}
|style=padding-left:1em;|{{nts|2}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|}}
|style=text-align:center;|<ref name="Ioualalen">{{cite journal|last1=Ioualalen|first1=M.|last2=Pelinovsky|first2=E.|last3=Asavanant|first3=J.|last4=Lipikorn|first4=R.|last5=Deschamps|first5=A.|year=2007|title=On the weak impact of the 26 December Indian Ocean tsunami on the Bangladesh coast|journal=Natural Hazards and Earth System Sciences|volume=7|issue=1|pages=141–147|doi=10.5194/nhess-7-141-2007|bibcode=2007NHESS...7..141I|doi-access=free}}</ref>
|-
|style=padding-left:1em;|{{flagdeco|South Africa}} [[Countries affected by the 2004 Indian Ocean earthquake#Countries suffering some casualties and damage|South Africa]]
|style=padding-left:1em;|{{nts|2}}{{ref label|e|e}}
|style=padding-left:1em;|{{nts|2}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|}}
|style=text-align:center;|<ref name="Okal">{{cite journal|author1=Okal, E.A.|author2=Hartnady C.J.|title=The South Sandwich Islands earthquake of 27 June 1929: seismological study and inference on tsunami risk for the southern Atlantic|journal=[[South African Journal of Geology]]|volume=112|pages=359–370|doi=10.2113/gssajg.112.3-4.359|url=http://www.africaarray.psu.edu/publications/pdfs/359_370%20Okal_Hartnady.pdf|access-date=26 June 2011|year=2010|issue=3–4|archive-date=17 April 2012|archive-url=https://web.archive.org/web/20120417062833/http://www.africaarray.psu.edu/publications/pdfs/359_370%20Okal_Hartnady.pdf|url-status=live}}</ref>
|-
|style=padding-left:1em;|{{flagdeco|Yemen}} [[Countries affected by the 2004 Indian Ocean earthquake#Countries suffering some casualties and damage|Yemen]]
|style=padding-left:1em;|{{nts|2}}
|style=padding-left:1em;|{{nts|2}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|}}
|style=text-align:center;|<ref>{{cite web|url=http://www.irinnews.org/report/24885/yemen-tsunami-damage-over-us-1-million-unep-assessment|title=YEMEN: Tsunami damage over US$1 million – UNEP assessment|via=The New Humanitarian|date=22 February 2005|access-date=24 December 2012|archive-date=26 March 2014|archive-url=https://web.archive.org/web/20140326175227/http://www.irinnews.org/report/24885/yemen-tsunami-damage-over-us-1-million-unep-assessment|url-status=live}}</ref>
|-
|style=padding-left:1em;|{{flagdeco|Kenya}} [[Countries affected by the 2004 Indian Ocean earthquake#Countries suffering some casualties and damage|Kenya]]
|style=padding-left:1em;|{{nts|1}}
|style=padding-left:1em;|{{nts|1}}
|style=padding-left:1em;|{{nts|2}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|}}
|style=text-align:center;|<!-- Please add reference -->
|-
|style=padding-left:1em;|{{flagdeco|Madagascar}} [[Countries affected by the 2004 Indian Ocean earthquake#Countries suffering damage only|Madagascar]]
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|}}
|style=padding-left:1em;|{{nts|1,000}}+
|style=text-align:center;|<ref>{{cite news|url=http://news.bbc.co.uk/1/hi/world/africa/4129639.stm|title=Tsunami devastates Somali island|publisher=BBC News|date=29 December 2004|access-date=24 December 2012|archive-date=10 February 2009|archive-url=https://web.archive.org/web/20090210044854/http://news.bbc.co.uk/1/hi/world/africa/4129639.stm|url-status=live}}</ref>
|-style=background-color:#eaecf0; class=sortbottom
|style=padding-left:1em;|'''Total estimates'''
|style=padding-left:1em;|'''184,167'''
|style=padding-left:1em;|'''227,898'''
|style=padding-left:1em;|'''125,000'''
|style=padding-left:1em;|'''43,789'''
|style=padding-left:1em;|'''1,740,000'''
|style=text-align:center;|<!-- Please add reference -->
|-style=font-size:85%; font-weight:normal; background-color:#f8f9fa; border-top:2px solid grey; class=sortbottom
|colspan="7" |{{Unbulleted list
|{{note|a|a}} This table refers only to countries directly affected by the tsunami, not to countries whose citizens were affected while overseas.
|{{note|b|b}} Includes those reported under 'Confirmed'. If no separate estimates are available, the number in this column is the same as reported under 'Confirmed'.
|{{note|c|c}} Does not include approximately 19,000 missing people initially declared by [[Tamil Tiger]] authorities from regions under their control.
|{{note|d|d}} Data includes at least 2,464 foreigners.
|{{note|e|e}} Does not include South African citizens who died outside of South Africa (e.g., tourists in Thailand).}}
|}

===Environmental impact===
[[File:TsunamiAftermathNorthofPhuket NASA.jpg|thumb|left|upright=1.2|Tsunami inundation in [[Khao Lak]], Thailand]]
Beyond the heavy toll on human lives, the Indian Ocean earthquake caused an enormous environmental impact that affected the region for many years. Severe damage was inflicted on [[ecosystem]]s such as mangroves, coral reefs, forests, coastal wetlands, vegetation, sand dunes and rock formations, animal and plant [[biodiversity]] and [[groundwater]]. Also, the spread of solid and liquid waste and industrial chemicals, water pollution and the destruction of [[sewage]] collectors and treatment plants threatened the environment even further. The environmental impact took a long time and significant resources to assess.<ref>{{cite web|title=Impact of Tsunamis on Ecosystems|work=United Nations Atlas of the Oceans|date=10 March 2005|url=http://www.oceansatlas.org/id/71687|archive-url=https://web.archive.org/web/20080820112413/http://www.oceansatlas.org/id/71687|url-status=dead|archive-date=20 August 2008}}</ref>

The main effect was caused by poisoning of the freshwater supplies and of the soil by saltwater infiltration and a deposit of a salt layer over arable land. In the Maldives, 16 to 17 coral reef atolls that were overcome by sea waves are without fresh water and could be rendered uninhabitable for decades. Uncountable wells that served communities were invaded by sea, sand, and earth, and [[aquifer]]s were invaded through porous rock. On the island's east coast, the tsunami contaminated wells on which many villagers relied for drinking water.<ref name="IWMI"/>

The Colombo-based [[International Water Management Institute]] monitored the effects of saltwater and concluded that the wells recovered to pre-tsunami drinking water quality one-and-a-half years after the event.<ref name="IWMI">{{cite journal|title=Helping restore the quality of drinking water after the tsunami|year=2010|url=http://www.iwmi.cgiar.org/Publications/Success_Stories/PDF/2010/Issue%207%20-%20Helping_restore_the_quality_of_drinking_water_after_the_tsunami.pdf|publisher=International Water Management Institute|journal=Success Stories|issue=10|access-date=11 August 2021|archive-date=2 March 2012|archive-url=https://web.archive.org/web/20120302022712/http://www.iwmi.cgiar.org/Publications/Success_Stories/PDF/2010/Issue%207%20-%20Helping_restore_the_quality_of_drinking_water_after_the_tsunami.pdf|url-status=live}}</ref> The [[International Water Management Institute|IWMI]] developed protocols for cleaning wells contaminated by saltwater; these were subsequently officially endorsed by the [[World Health Organization]] as part of its series of Emergency Guidelines.<ref>[https://www.who.int/water_sanitation_health/hygiene/envsan/technotes/en/ Water sanitation and health: WHO technical notes for emergencies.] {{webarchive|url=https://web.archive.org/web/20160212053301/http://www.who.int/water_sanitation_health/hygiene/envsan/technotes/en/ |date=12 February 2016 }} Page. Retrieved 25 February 2011</ref>

Salted-over soil becomes sterile, and it is difficult and costly to restore for agriculture. It also causes the death of plants and important soil micro-organisms. Thousands of rice, mango, and banana plantations in Sri Lanka were destroyed almost entirely and will take years to recover.<ref name="IWMI"/>

In addition to other forms of aid,<ref>{{cite web|title=Indian Ocean tsunami|date=19 December 2014|url=https://www.dfat.gov.au/news/news/Pages/indian-ocean-tsunami|website=Department of Foreign Affairs and Trade, Australian Government|access-date=11 August 2021|archive-date=11 August 2021|archive-url=https://web.archive.org/web/20210811212536/https://www.dfat.gov.au/news/news/Pages/indian-ocean-tsunami|url-status=live}}</ref> the Australian government sent ecological experts to help develop strategies for reef-monitoring and rehabilitation of marine environments and coral reefs in the Maldives, Seychelles and other areas. Scientists had developed significant ecological expertise from work with the [[Great Barrier Reef]], in Australia's northeastern waters.<ref name="Australia">{{cite book|title=Australia's response to the Indian Ocean tsunami REPORT FOR THE PERIOD ENDING 30 JUNE 2005|date=2005|publisher=Commonwealth of Australia|url=https://reliefweb.int/sites/reliefweb.int/files/resources/34F36A2FE297C7BD49257074001D828E-ausaid-tsunami-06sep.pdf|access-date=11 August 2021|archive-date=11 August 2021|archive-url=https://web.archive.org/web/20210811211831/https://reliefweb.int/sites/reliefweb.int/files/resources/34F36A2FE297C7BD49257074001D828E-ausaid-tsunami-06sep.pdf|url-status=live}}</ref>

In response to the unprecedented situation, the [[United Nations Environment Programme]] (UNEP) worked with governments in the region to determine the severity of the ecological impact and how to address it.<ref>{{cite web|title=Environmental Issues Emerging from Wreckage of Asian Tsunami|url=https://www.un.org/press/en/2004/unep255.doc.htm|publisher=United Nations|access-date=3 October 2019|archive-url=https://web.archive.org/web/20050111221153/http://www.unep.org/Documents.Multilingual/Default.asp?DocumentID=414&ArticleID=4692&l=en|archive-date=11 January 2005|date=30 December 2004|url-status=unfit}}</ref> UNEP established an emergency fund, set up a Task Force to respond to requests for assistance from countries affected by the tsunami, and was able to mobilize and distribute approximately US$9.3 million for environmental recovery and disaster risk reduction between 2004 and 2007. Funding came from other international agencies and from countries including Finland, Norway, Spain, Sweden and the United Kingdom.<ref name="UNEP2008">{{cite book|title=UNEP Post-Tsunami Recover y Activities 2004-2007|date=2008|publisher=UNEP Post-Tsunami Recover y Activities 2004-2007 United Nations Environment Programme|url=https://postconflict.unep.ch/publications/PT_recovery.pdf|access-date=11 August 2021|archive-date=11 August 2021|archive-url=https://web.archive.org/web/20210811210519/https://postconflict.unep.ch/publications/PT_recovery.pdf|url-status=live}}</ref><ref>{{cite web|url=http://www.unep.org/Documents.Multilingual/Default.asp?DocumentID=434&ArticleID=4818&l=en|title=United Nations Environment Programme; Environment for Development|access-date=22 April 2006|archive-url=http://webarchive.loc.gov/all/20060412095140/http://www.unep.org/Documents.Multilingual/Default.asp?DocumentID=434&ArticleID=4818&l=en|archive-date=12 April 2006|url-status=live}}</ref>

Evidence suggested that the presence of [[mangroves]] in coastal areas had provided some protection, when compared to areas that had been cleared for aquaculture or development. As a result, [[mangrove restoration]] become a focus of a number of projects, with varied success. Such approaches to [[ecosystem-based disaster risk reduction]] appear to be most successful when local communities are closely involved as stakeholders throughout the process, and when careful attention is paid to the physical conditions of chosen sites to ensure that mangroves can thrive there.<ref name="Zimmer">{{cite journal|last1=Zimmer|first1=Katarina|title=Many mangrove restorations fail. Is there a better way?|journal=Knowable Magazine|date=22 July 2021|doi=10.1146/knowable-072221-1|url=https://knowablemagazine.org/article/food-environment/2021/many-mangrove-restorations-fail|access-date=11 August 2021|doi-access=free|archive-date=16 August 2021|archive-url=https://web.archive.org/web/20210816114657/https://knowablemagazine.org/article/food-environment/2021/many-mangrove-restorations-fail|url-status=live|url-access=subscription}}</ref>

===Economic impact===
[[File:Chennai beach2.jpg|thumb|upright=1.2|[[Chennai]]'s [[Marina Beach]] after the tsunami]]
The level of damage to the economy resulting from the tsunami depends on the scale examined. While the overall impact on the national economies was minor, local economies were devastated. The two main occupations most affected by the tsunami were fishing and tourism.<ref>{{cite journal|last=Gunatillake|first=Daya|title=The 2004 Tsunami in Sri Lanka: Destruction and recovery|journal=Geography|year=2007|volume=92|issue=3|pages=285–293|doi=10.1080/00167487.2007.12094208|jstor=40574342}}</ref> Some economists believe that damage to the affected national economies will be minor because losses in the tourism and fishing industries are a relatively small percentage of the GDP. However, others caution that damage to infrastructure is an overriding factor. In some areas drinking water supplies and farm fields may have been contaminated for years by saltwater from the ocean.<ref>Pearce, Fred. "[https://www.newscientist.com/article.ns?id=dn6840 Tsunami's salt water may leave islands uninhabitable]." ''[[New Scientist]].'' 5 January 2005. {{webarchive |url=https://web.archive.org/web/20080422084629/http://www.newscientist.com/article.ns?id=dn6840 |date=22 April 2008 }}</ref>

The impact on coastal fishing communities and the people living there, some of the poorest in the region, has been devastating with high losses of income earners as well as boats and fishing gear.<ref>{{cite web|url=http://www.ukabc.org/tsunamis.htm|title=Tsunamis Devastate Fisherfolk of Indian Ocean and Arabian Sea|website=ukabc.org|access-date=11 March 2019|archive-date=3 March 2019|archive-url=https://web.archive.org/web/20190303024418/http://www.ukabc.org/tsunamis.htm|url-status=live}}</ref><ref>{{cite web|url=https://reliefweb.int/sites/reliefweb.int/files/resources/70B417968D5FCDD0C1256F8400498CE6-fao-souasi-7jan.pdf|title=Impacts of the Tsunami on Fisheries, Aquaculture and Coastal Livelihoods|date=7 January 2005|publisher=ReliefWeb|access-date=10 March 2019|archive-date=8 March 2021|archive-url=https://web.archive.org/web/20210308062132/https://reliefweb.int/sites/reliefweb.int/files/resources/70B417968D5FCDD0C1256F8400498CE6-fao-souasi-7jan.pdf|url-status=live}}</ref> In Sri Lanka, artisanal fishery, in which the use of fish baskets, fishing traps, and spears are commonly used, is an important source of fish for local markets; industrial fishery is the major economic activity, providing direct employment to about 250,000 people. In recent years the fishery industry has emerged as a dynamic export-oriented sector, generating substantial foreign exchange earnings. Preliminary estimates indicated that 66% of the fishing fleet and industrial infrastructure in coastal regions were destroyed by the wave surges.<ref>{{cite web|url=https://reliefweb.int/report/indonesia/food-supply-and-food-security-situation-countries-affected-asia-tsunami|title=Food supply and food security situation in countries affected by the Asia tsunami – Indonesia|publisher=ReliefWeb|date=18 February 2005|access-date=11 March 2019|archive-date=21 January 2020|archive-url=https://web.archive.org/web/20200121122102/https://reliefweb.int/report/indonesia/food-supply-and-food-security-situation-countries-affected-asia-tsunami|url-status=live}}</ref>

While the tsunami destroyed many of the boats vital to Sri Lanka's fishing industry, it also created a demand for fibreglass-reinforced plastic catamarans in the boatyards of [[Tamil Nadu]]. Given that over 51,000 vessels were lost to the tsunami, the industry boomed. However, the huge demand has led to lower quality in the process, and some important materials were sacrificed to cut prices for those who were impoverished by the tsunami.<ref>{{cite web|url=http://www.bobpigo.org/bbn/sep_06/pages10-12.pdf|archive-url=https://web.archive.org/web/20110624095558/http://www.bobpigo.org/bbn/sep_06/pages10-12.pdf|archive-date=24 June 2011|title=Demand for FRP boats rise after tsunami|access-date=12 August 2010|url-status=dead}}</ref>

Even though only coastal regions were directly affected by the waters of the tsunami, the indirect effects have spread to inland provinces as well. Since the media coverage of the event was so extensive, many tourists cancelled vacations and trips to that part of the world, even though their travel destinations may not have been affected. This ripple effect could especially be felt in the inland provinces of Thailand, such as Krabi, which acted as a starting point for many other tourist destinations in Thailand.<ref>{{cite journal|author1=Rigg, Johnathan|author2=Lisa Lawt|author3=May Tan-Mullins|author4=Carl Grundy-Warr|title=The Indian Ocean Tsunami: Socio-Economic Impacts in Thailand.|journal=The Geographical Journal|date=December 2005|volume=171|issue=4|pages=374–379|jstor=3451210|doi=10.1111/j.1475-4959.2005.00175_3.x|bibcode=2005GeogJ.171..374R|url=http://dro.dur.ac.uk/1284/1/1284.pdf?DDD14+dgg0cnm|access-date=20 March 2019|archive-date=24 July 2020|archive-url=https://web.archive.org/web/20200724141017/http://dro.dur.ac.uk/1284/1/1284.pdf?DDD14+dgg0cnm|url-status=live}}</ref>

Countries in the region appealed to tourists to return, pointing out that most tourist infrastructure is undamaged. However, tourists were reluctant to do so for psychological reasons. Even beach resorts in parts of Thailand which were untouched by the tsunami were hit by cancellations.<ref>Chapter 6, "Thailand", in Jayasuriya, Sisira and Peter McCawley, [http://www.e-elgar.co.uk/Bookentry_Main.lasso?id=13668 ''The Asian Tsunami: Aid and Reconstruction after a Disaster''] {{Webarchive|url=https://web.archive.org/web/20110722005138/http://www.e-elgar.co.uk/Bookentry_Main.lasso?id=13668 |date=22 July 2011 }}. Cheltenham UK and Northampton MA: Edward Elgar, 2010.</ref>

Both the earthquake and the tsunami may have affected shipping in the [[Malacca Straits]], which separate Malaysia and the Indonesian island of Sumatra, by changing the depth of the seabed and by disturbing navigational buoys and old shipwrecks. In one area of the Strait, water depths were previously up to {{cvt|4000|ft|m|order=flip}}, and are now only {{cvt|100|ft|m|order=flip}} in some areas, making shipping impossible and dangerous. These problems also made the delivery of relief aid more challenging. Compiling new navigational charts may take months or years. Officials also hoped that piracy in the region would drop off, since the tsunami had killed pirates and destroyed their boats.<ref>Staff Writer. "[https://www.nbcnews.com/id/wbna6791600 Tsunami redrew ship channels, ocean floor]." [[NBC News]]/Associated Press. 5 January 2005.</ref> Due to multiple factors, there was a 71.6% drop in the number of piracy incidents between 2004 and 2005, from 60 to 17 incidents.  Levels remained relatively low for some years. However, between 2013 and 2014, piracy incidents rose dramatically by 73.2% to exceed pre-tsunami levels.<ref>{{cite web|last1=Birchard|first1=Emma Louise|title=Piracy in the Strait of Malacca: The geopolitical background behind piracy and its impacts on Global Financial Centres|url=https://theses.ubn.ru.nl/bitstream/handle/123456789/10228/Birchard%2C_Emma_Louise_1.pdf?sequence=1|publisher=Radboud University|year=2020|access-date=11 August 2021|archive-date=11 August 2021|archive-url=https://web.archive.org/web/20210811200130/https://theses.ubn.ru.nl/bitstream/handle/123456789/10228/Birchard,_Emma_Louise_1.pdf?sequence=1|url-status=live}}</ref>

===Historical context===
{{See also|Library damage resulting from the 2004 Indian Ocean earthquake}}
{{Location map+|Indonesia Sumatra|float=right|alt=Earthquakes in Sumatra|caption=Of the ten strongest [[List of earthquakes in Indonesia|Indonesian earthquakes]] ≥ 8.3 M<sub>w</sub>, six occurred near Sumatra|places=
{{Location map~|Indonesia Sumatra|lat=3.316|long=95.854|position=right|label=<div style="position: relative; top: 0.4em;">2004</div>}}
{{Location map~|Indonesia Sumatra|lat=-2.5|long=100.5|position=right|label=<div style="position: relative; top: 0.4em;">[[1833 Sumatra earthquake|1833]]</div>}}
{{Location map~|Indonesia Sumatra|lat=2.09|long=97.15|position=right|label=<div style="position: relative; top: 0.4em;">[[2005 Nias–Simeulue earthquake|2005]]</div>}}
{{Location map~|Indonesia Sumatra|lat=1.0|long=97.5|position=right|label=<div style="position: relative; top: 0.4em;">[[1861 Sumatra earthquake|1861]]</div>}}
{{Location map~|Indonesia Sumatra|lat=-4.52|long=101.374|position=right|label=<div style="position: relative; top: 0.4em;">[[2007 Bengkulu earthquakes|2007]]</div>}}
{{Location map~|Indonesia Sumatra|lat=-1.0|long=99.0|position=right|label=<div style="position: relative; top: 0.4em;">[[1797 Sumatra earthquake|1797]]</div>}}
}}
The last major tsunami in the Indian Ocean was about A.D. 1400.<ref>{{cite news|last=Palmer|first=Jason|url=http://news.bbc.co.uk/1/hi/sci/tech/7697482.stm|title=Tsunami in 2004 'not the first'|publisher=BBC News|date=29 October 2008|access-date=12 August 2010|archive-date=15 February 2009|archive-url=https://web.archive.org/web/20090215121702/http://news.bbc.co.uk/1/hi/sci/tech/7697482.stm|url-status=live}}</ref><ref>{{cite news|url=http://www.radioaustralia.net.au/international/2008-10-30/researchers-uncover-2004-tsunami-predecessor/35702|title=Researchers uncover 2004 tsunami predecessor|work=ABC Radio Australia News|date=30 October 2008|access-date=13 April 2011|archive-date=17 December 2013|archive-url=https://web.archive.org/web/20131217213901/http://www.radioaustralia.net.au/international/2008-10-30/researchers-uncover-2004-tsunami-predecessor/35702|url-status=live}}</ref> In 2008, a team of scientists working on Phra Thong, a barrier island along the hard-hit west coast of Thailand, reported evidence of at least three previous major tsunamis in the preceding 2,800 years, the most recent from about 700 years ago. A second team found similar evidence of previous tsunamis in Aceh, a province at the northern tip of [[Sumatra]]; radiocarbon dating of bark fragments in the soil below the second sand layer led the scientists to estimate that the most recent predecessor to the 2004 tsunami probably occurred between A.D. 1300 and 1450.<ref>{{cite web|url=http://newswise.com/articles/view/545772/|title=Scientists Find Evidence of Tsunamis on Indian Ocean Shores Long Before 2004|publisher=Newswise.com|date=27 October 2008|access-date=24 December 2012|archive-date=31 May 2013|archive-url=https://web.archive.org/web/20130531090402/http://newswise.com/articles/view/545772/|url-status=live}}</ref>

The 2004 earthquake and tsunami combined is the [[List of natural disasters by death toll|world's deadliest]] natural disaster since the 1976 [[Tangshan earthquake]]. The earthquake was the third-most-powerful earthquake recorded since 1900. The deadliest-known earthquake in history occurred in [[1556 Shaanxi earthquake|1556 in Shaanxi, China]], with an estimated death toll of 830,000, though figures from this period may not be as reliable.<ref name="usgs1">{{cite web|url=https://earthquake.usgs.gov/regional/world/most_destructive.php|title=Most Destructive Known Earthquakes on Record in the World (Earthquakes with 50,000 or More Deaths)|publisher=United States Geological Survey|archive-url=https://web.archive.org/web/20090901233953/http://earthquake.usgs.gov/regional/world/most_destructive.php|archive-date=1 September 2009}}</ref>

Before 2004, the tsunami created in both Indian and Pacific Ocean waters by the 1883 eruption of [[Krakatoa]], thought to have resulted in anywhere from 36,000 to 120,000 deaths, had probably been the deadliest in the region. In 1782, about 40,000 people are thought to have been killed by a tsunami (or a cyclone) in the [[South China Sea]].<ref>{{cite journal|last1=Lau|first1=A. Y. A.|last2=Switzer|first2=A. D.|last3=Dominey-Howes|first3=D.|last4=Aitchison|first4=J. C.|last5=Zong|first5=Y.|title=Written records of historical tsunamis in the northeastern South China Sea – challenges associated with developing a new integrated database|journal=Natural Hazards and Earth System Sciences|date=1 September 2010|volume=10|issue=9|pages=1793–1806|doi=10.5194/nhess-10-1793-2010|url=http://www.nat-hazards-earth-syst-sci.net/10/1793/2010/nhess-10-1793-2010.pdf|bibcode=2010NHESS..10.1793L|doi-access=free|access-date=6 August 2013|archive-date=6 July 2020|archive-url=https://web.archive.org/web/20200706180220/https://www.nat-hazards-earth-syst-sci.net/10/1793/2010/nhess-10-1793-2010.pdf|url-status=live}}</ref> <!-- Comment... including a quantity and source uniformly regarded as invalid (typographical error) insofar as quantity... Not Awa, Japan 1703, alleged 100,000, which is probably a misreading of the 10,000 toll given in Watanabe, H., 1998, "Nihon higai tsunami so_ran, dai ni-han " (Comprehensive list of destructive tsunamis to hit the Japanese islands, 2ndedition) Tokyo, University of Tokyo Press, p. 238 end comment --> The deadliest tsunami before 2004 was Italy's [[1908 Messina earthquake]] on the [[Mediterranean Sea]] where the earthquake and tsunami killed about 123,000.<ref>{{cite web|url=https://www.cbc.ca/news/world/the-world-s-worst-natural-disasters-1.743208|title=The world's worst natural disasters|publisher=CBC News|date=31 August 2010|access-date=19 October 2019|archive-date=19 January 2011|archive-url=https://web.archive.org/web/20110119154212/http://www.cbc.ca/world/story/2008/05/08/f-natural-disasters-history.html|url-status=live}}</ref>

===Other effects===
[[File:Tsunami 2004 aftermath. Aceh, Indonesia, 2005. Photo- AusAID (10730863873).jpg|thumb|upright=1.2|Tsunami aftermath in Aceh, Indonesia]]

Many health professionals and aid workers have reported widespread psychological trauma associated with the tsunami.<ref>{{Cite journal|last1=Frankenberg|first1=Elizabeth|last2=Friedman|first2=Jed|last3=Gillespie|first3=Thomas|last4=Ingwersen|first4=Nicholas|last5=Pynoos|first5=Robert|last6=Rifai|first6=Iip Umar|last7=Sikoki|first7=Bondan|last8=Steinberg|first8=Alan|last9=Sumantri|first9=Cecep|last10=Suriastini|first10=Wayan|last11=Thomas|first11=Duncan|date=September 2008|title=Mental Health in Sumatra After the Tsunami|journal=American Journal of Public Health|volume=98|issue=9|pages=1671–1677|doi=10.2105/AJPH.2007.120915|issn=0090-0036|pmc=2509591|pmid=18633091}}</ref> Even 14 years afterwards, researchers find [[HPA axis]] dysregulation and "burnout" in survivors.<ref name="Lawton Frankenberg Seeman Crimmins 2023 p.">{{cite journal|last1=Lawton|first1=Ralph|last2=Frankenberg|first2=Elizabeth|last3=Seeman|first3=Teresa|last4=Crimmins|first4=Eileen|last5=Sumantri|first5=Cecep|last6=Thomas|first6=Duncan|date=16 October 2023|title=Exposure to the Indian Ocean Tsunami shapes the HPA-axis resulting in HPA "burnout" 14 years later|journal=Proceedings of the National Academy of Sciences|volume=120|issue=44|article-number=e2306497120|doi=10.1073/pnas.2306497120|pmid=37844215|pmc=10622908|bibcode=2023PNAS..12006497L|issn=0027-8424|doi-access=free}}</ref> Traditional beliefs in many of the affected regions state that a relative of the family must bury the body of the dead, and in many cases, no body remained to be buried.

The hardest-hit area, [[Aceh]], is a religiously conservative Islamic society and has had no tourism nor any Western presence in recent years due to the [[Insurgency in Aceh|insurgency]] between the [[Indonesian National Armed Forces|Indonesian military]] and [[Free Aceh Movement]] (GAM). Some believe that the tsunami was divine punishment for lay Muslims shirking their daily prayers or following a materialistic lifestyle. Others have said that Allah was angry that Muslims were killing each other in an ongoing conflict.<ref>Broadway, Bill. "[https://www.washingtonpost.com/wp-dyn/articles/A57758-2005Jan7.html Divining a Reason for Devastation]"; {{Webarchive|url=https://web.archive.org/web/20170914005421/http://www.washingtonpost.com/wp-dyn/articles/A57758-2005Jan7.html |date=14 September 2017 }}. ''[[The Washington Post]]''. 8 January 2005.</ref> Saudi cleric [[Muhammad Al-Munajjid]] attributed it to divine retribution against non-Muslim vacationers "who used to sprawl all over the beaches and in pubs overflowing with wine" during Christmas break.<ref>{{Cite web|url=https://www.baylor.edu/mediacommunications/index.php?id=25982|title=Associated Press û Tsunami survivors cling tightly to faith across ravaged region|website=Baylor University|access-date=11 March 2019|archive-date=24 July 2020|archive-url=https://web.archive.org/web/20200724140458/https://www.baylor.edu/mediacommunications/index.php?id=25982|url-status=live}}</ref>

The widespread devastation caused by the tsunami led GAM to declare a cease-fire on 28 December 2004 followed by the Indonesian government, and the two groups resumed long-stalled peace talks, which resulted in a peace agreement signed 15 August 2005. The agreement explicitly cites the tsunami as a justification.<ref>{{cite news|url=http://news.bbc.co.uk/1/shared/bsp/hi/pdfs/15_08_05_aceh.pdf|title=Memorandum of Understanding between Indonesian government and the Free Aceh Movement|date=15 August 2005|access-date=24 December 2012|publisher=BBC News|archive-date=29 June 2006|archive-url=https://web.archive.org/web/20060629202428/http://news.bbc.co.uk/1/shared/bsp/hi/pdfs/15_08_05_aceh.pdf|url-status=live}}</ref>

In a poll conducted in 27 countries, 15% of respondents named the tsunami the most significant event of the year. Only the [[Iraq War]] was named by as many respondents.<ref>{{cite news|url=http://news.bbc.co.uk/2/shared/bsp/hi/pdfs/30_12_05_ws_events_poll.pdf|title=Most significant events of 2005|date=30 December 2005|publisher=BBC World Service|access-date=26 September 2013|archive-date=2 October 2013|archive-url=https://web.archive.org/web/20131002211446/http://news.bbc.co.uk/2/shared/bsp/hi/pdfs/30_12_05_ws_events_poll.pdf|url-status=live}}, and {{cite news|url=http://news.bbc.co.uk/2/hi/europe/4566826.stm|title=Iraq war and tsunami top BBC poll|date=30 December 2005|publisher=BBC World Service|access-date=26 September 2013|archive-date=2 October 2013|archive-url=https://web.archive.org/web/20131002213901/http://news.bbc.co.uk/2/hi/europe/4566826.stm|url-status=live}}</ref><ref>{{cite book|last1=Brighton|first1=Paul|last2=Foy|first2=Dennis|title=News Values|year=2007|publisher=Sage|location=London|isbn=978-1412946001|page=44}}</ref> The extensive international media coverage of the tsunami, and the role of mass media and journalists in reconstruction, were discussed by editors of newspapers and broadcast media in tsunami-affected areas, in special video-conferences set up by the Asia Pacific Journalism Centre.<ref>{{cite web|url=http://www.apjc.org.au/program6.html|title=Asia Pacific Journalism Centre&nbsp;– Home Page|access-date=24 October 2007|archive-url=https://web.archive.org/web/20071013035339/http://www.apjc.org.au/program6.html|archive-date=13 October 2007|url-status=dead}}</ref>

The tsunami left both the people and government of India in a state of heightened alert. On 30 December 2004, four days after the tsunami, Terra Research notified the India government that its sensors indicated there was a possibility of 7.9 to 8.1 magnitude tectonic shift in the next 12 hours between Sumatra and New Zealand.<ref name="Press">[[Press Trust of India]] (30 December 2004) "Alert scaled down, capping day long confusion."</ref> In response, the Indian [[Minister of Home Affairs (India)|Minister of Home Affairs]] announced that a fresh onslaught of deadly tsunami was likely along the southern Indian coast and the [[Andaman Islands|Andaman]] and [[Nicobar Islands]], even as there was no sign of turbulence in the region.<ref name="Press"/> The announcement generated panic in the Indian Ocean region and caused thousands to flee their homes, which resulted in jammed roads.<ref name="Tran">Tran, Tina. (30 December 2004) [[Associated Press]] "[http://www.signonsandiego.com/news/world/20041230-1108-tsunami-falsewarning.html False tsunami alarm sparks panic in Indian Ocean region.] {{webarchive|url=https://web.archive.org/web/20090621044212/http://www.signonsandiego.com/news/world/20041230-1108-tsunami-falsewarning.html |date=21 June 2009 }}"</ref> The announcement was a false alarm, and the Home Affairs minister withdrew their announcement.<ref name="Tran"/> On further investigation, the India government learned that the consulting company Terra Research was run from the home of a self-described [[Earthquake prediction|earthquake forecaster]] who had no telephone listing and maintained a website where he sold copies of his detection system.<ref>{{cite news|url=https://www.seattletimes.com/nation-world/suspect-quake-forecast-causes-panic/|title=Suspect quake forecast causes panic|work=The Seattle Times|via=Associated Press|date=31 December 2004|access-date=17 October 2019|archive-date=16 October 2019|archive-url=https://web.archive.org/web/20191016170754/https://www.seattletimes.com/nation-world/suspect-quake-forecast-causes-panic/|url-status=live}}</ref>

[[File:Phuket after tsunami (2004).jpg|thumb|upright=1.1|Patong Beach in Thailand after the tsunami]]

The tsunami had a severe humanitarian and political impact in Sweden. The hardest-hit country outside Asia, Sweden, lost 543 tourists, mainly in Thailand. The [[Persson Cabinet]] was heavily criticized for its inaction.<ref>{{cite news|title=Ministers Admit Handling of Tsunami Crisis Caused Suffering – Radio Sweden|url=https://sverigesradio.se/artikel/797579|access-date=15 December 2020|publisher=Sveriges Radio|date=16 February 2006|archive-date=25 July 2021|archive-url=https://web.archive.org/web/20210725132232/https://sverigesradio.se/artikel/797579|url-status=live}}</ref>

[[Smith Dharmasaroja]], a meteorologist who had predicted that an earthquake and [[tsunami]] "is going to occur for sure" in 1994,<ref>{{Cite web|url=https://www.seapa.org/mad-scientist-gets-belated-recognition/|title='Mad' Scientist Gets Belated Recognition|publisher=Southeast Asian Press Alliance|last=Tima|first=Raffy Jr.|date=12 May 2010|archive-url=https://web.archive.org/web/20180319031526/https://www.seapa.org/mad-scientist-gets-belated-recognition/|archive-date=19 March 2018}}</ref><ref>{{Cite web|url=http://www.internationalist.org/disasterforetold0501.html|title=A 'Natural Disaster' Foretold|work=The Internationalist|date=January 2005|access-date=16 December 2020|archive-date=26 February 2021|archive-url=https://web.archive.org/web/20210226132458/http://www.internationalist.org/disasterforetold0501.html|url-status=live}}</ref> was assigned the development of the Thai tsunami warning system. The [[Indian Ocean Tsunami Warning System]] was formed in early 2005 to provide an early warning of tsunamis for inhabitants around the Indian Ocean coasts.<ref>{{Cite web|url=http://iotic.ioc-unesco.org/indian-ocean-tsunami-warning-system/16/what-is-iotws|title=What is IOTWS|website=IOTWS|access-date=11 March 2019|archive-date=27 February 2019|archive-url=https://web.archive.org/web/20190227214133/http://iotic.ioc-unesco.org/indian-ocean-tsunami-warning-system/16/what-is-iotws|url-status=live}}</ref>

The changes in the distribution of masses inside the Earth due to the earthquake had several consequences. It [[polar motion|displaced the North Pole]] by {{cvt|25|mm}}. It also slightly changed the shape of the Earth, specifically by decreasing Earth's oblateness by about one part in 10 billion, consequentially increasing [[Earth's rotation]] a little and thus shortening the length of the day by 2.68 microseconds.<ref name="NASA" />

The Indian Ocean Tsunami Archives were added to the UNESCO [[Memory of the World Register – Asia and the Pacific|Memory of the World register]] in 2017.<ref name=":2">{{Cite web |title=The Indian Ocean Tsunami Archives |url=https://www.unesco.org/en/memory-world/indian-ocean-tsunami-archives?hub=1081 |access-date=9 September 2025 |website=UNESCO Memory of the World}}</ref> The archive consists of video, audio, and photographs.<ref name=":2" />

==Humanitarian response==
{{Main|Humanitarian response to the 2004 Indian Ocean earthquake}}

[[File:German Tsunami Relief Mission Team in Mullaitivu.jpg|thumb|upright=1.1|German tsunami relief mission visiting [[Mullaitivu]] in Sri Lanka's [[Northern Province, Sri Lanka|Northern Province]]]]

A great deal of [[humanitarian aid]] was needed because of widespread damage to the infrastructure, shortages of food and water, and economic damage. Epidemics were of particular concern due to the high population density and tropical climate of the affected areas. The main concern of humanitarian and government agencies was to provide sanitation facilities and fresh drinking water to contain the spread of diseases such as [[cholera]], [[diphtheria]], [[dysentery]], [[typhoid]] and [[hepatitis A]] and {{nowrap|[[hepatitis B]]}}.

There was also a great concern that the death toll could increase as disease and hunger spread. However, because of the initial quick response, this was minimized.<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/asia-pacific/4157947.stm|title=UN upbeat on tsunami hunger aid|publisher=BBC News|date=9 January 2005|access-date=24 December 2012|archive-date=12 April 2013|archive-url=https://web.archive.org/web/20130412065431/http://news.bbc.co.uk/2/hi/asia-pacific/4157947.stm|url-status=live}}</ref>

In the days following the tsunami, significant effort was spent in burying bodies hurriedly due to fear of disease spreading. However, the public health risks may have been exaggerated, and therefore this may not have been the best way to allocate resources.<ref>{{cite journal|last1=Ball|first1=Philip|title=Mass graves not necessary for tsunami victims|journal=[[Nature (journal)|Nature]]|date=7 January 2005|doi=10.1038/news050103-10|url=https://www.nature.com/articles/news050103-10|access-date=13 September 2023|url-access=subscription}}</ref><ref>{{cite web|title=Health Effects of Tsunamis|url=https://www.cdc.gov/disasters/tsunamis/healtheff.html|website=Natural Disasters and Severe Weather|publisher=[[Centers for Disease Control and Prevention]]|access-date=13 September 2023|archive-date=31 August 2023|archive-url=https://web.archive.org/web/20230831082145/https://www.cdc.gov/disasters/tsunamis/healtheff.html|url-status=live}}</ref> The [[World Food Programme]] provided food aid to more than 1.3 million people affected by the tsunami.<ref>{{cite web|url=http://reliefweb.int/report/indonesia/wfp-situation-report-tsunami-crisis-indian-ocean-region-friday-4-nov-2005|title=United Nations: World Food Programme: Report on the Tsunami Crisis|publisher=ReliefWeb|date=4 November 2005|access-date=24 December 2012|archive-date=12 December 2013|archive-url=https://web.archive.org/web/20131212221140/http://reliefweb.int/report/indonesia/wfp-situation-report-tsunami-crisis-indian-ocean-region-friday-4-nov-2005|url-status=live}}</ref>
{{Further|Health risks from dead bodies}}

Nations all over the world provided over US$14 billion in aid for damaged regions,<ref>Chapter 3, "The matter of money", in Jayasuriya, Sisira and Peter McCawley, [http://www.e-elgar.co.uk/Bookentry_Main.lasso?id=13668 "The Asian Tsunami: Aid and Reconstruction after a Disaster"] {{Webarchive|url=https://web.archive.org/web/20110722005138/http://www.e-elgar.co.uk/Bookentry_Main.lasso?id=13668 |date=22 July 2011 }}. Cheltenham UK and Northampton MA: Edward Elgar, 2010.</ref> with the governments of Australia pledging US$819.9 million (including a US$760.6 million aid package for Indonesia), Germany offering US$660 million, Japan offering US$500 million, Canada offering US$343 million, Norway and the Netherlands offering both US$183 million, the United States offering US$35 million initially (increased to US$350 million), and the [[World Bank]] offering US$250 million. Also, Italy offered US$95 million, increased later to US$113 million of which US$42 million was donated by the population using the SMS system.<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/asia-pacific/4145259.stm|title=Tsunami aid: Who's giving what|date=27 January 2005|access-date=22 April 2006|publisher=BBC News|archive-date=22 June 2006|archive-url=https://web.archive.org/web/20060622072742/http://news.bbc.co.uk/2/hi/asia-pacific/4145259.stm|url-status=live}}</ref> Australia, India, Japan and the United States formed an ad-hoc corroborative group, and it was the origin of [[Quadrilateral Security Dialogue]].<ref name="Madan_2017">{{cite web|url=https://warontherocks.com/2017/11/rise-fall-rebirth-quad/|date=16 November 2017|author=Tanvi Madan|title=The Rise, Fall, and Rebirth of the 'Quad'|website=War on the Rocks|access-date=22 February 2021|archive-date=13 February 2021|archive-url=https://web.archive.org/web/20210213000755/https://warontherocks.com/2017/11/rise-fall-rebirth-quad/|url-status=live}}</ref>

[[File:Tsunami disaster memorial plaque in Batticaloa.jpg|thumb|upright=1.1|Memorial dedicated to victims of the tsunami in [[Batticaloa]], Sri Lanka, written in Tamil]]

According to [[USAID]], the US has pledged additional funds in long-term U.S. support to help the tsunami victims rebuild their lives. On 9 February 2005, President Bush asked Congress to increase the U.S. commitment to a total of US$950 million. Officials estimated that billions of dollars would be needed. Bush also asked his father, former president George H. W. Bush, and former president Bill Clinton to lead a U.S. effort to provide private aid to the tsunami victims.<ref>Staff Writer. "[https://www.cbsnews.com/news/clinton-bush-tsunami-aid-helping/ Clinton, Bush: Tsunami Aid Helping]". ''[[The Early Show]]''/[[CBS News]]. 21 February 2005.</ref>

In mid-March, the [[Asian Development Bank]] reported that over US$4 billion in aid promised by governments was behind schedule. Sri Lanka reported that it had received no foreign government aid, while foreign individuals had been generous.<ref>Staff Writer. "[http://news.bbc.co.uk/2/hi/asia-pacific/4361053.stm Tsunami aid shortfall over $4bn] {{Webarchive|url=https://web.archive.org/web/20050912233919/http://news.bbc.co.uk/2/hi/asia-pacific/4361053.stm |date=12 September 2005 }}." BBC News. 18 March 2005.</ref> Many charities were given considerable donations from the public. For example, in the United Kingdom, the public donated roughly £330 million sterling (nearly US$600 million). This considerably outweighed the allocation by the government to disaster relief and reconstruction of £75 million and came to an average of about £5.50 (US$10) donated by every citizen.<ref>{{Cite journal|last1=Telford|first1=John|last2=Cosgrave|first2=John|date=March 2007|title=The international humanitarian system and the 2004 Indian Ocean earthquake and tsunamis|journal=Disasters|volume=31|issue=1|pages=1–28|doi=10.1111/j.1467-7717.2007.00337.x|pmid=17367371|bibcode=2007Disas..31....1T|doi-access=free}}</ref><ref>{{Cite web|url=https://www.unocha.org/sites/dms/Documents/TEC_Funding_Report.pdf|title=Funding the Tsunami Response|last=Flint|first=Michael|date=July 2006|publisher=United Nations Office for the Coordination of Humanitarian Affairs|access-date=11 March 2019|archive-date=12 January 2019|archive-url=https://web.archive.org/web/20190112080859/https://www.unocha.org/sites/dms/Documents/TEC_Funding_Report.pdf|url-status=live}}</ref>

In August 2006, fifteen local aid staff working on post-tsunami rebuilding were found executed in north-east Sri Lanka after heavy fighting between government troops and the Tamil Tiger rebels, the main umbrella body for aid agencies in the country said.<ref>{{Cite news|url=https://www.theguardian.com/world/2006/aug/07/tsunami2004.internationalaidanddevelopment|title=15 tsunami aid staff executed in Sri Lanka|last1=Ramesh|first1=Randeep|date=7 August 2006|work=The Guardian|access-date=11 March 2019|issn=0261-3077|archive-date=4 May 2020|archive-url=https://web.archive.org/web/20200504175225/https://www.theguardian.com/world/2006/aug/07/tsunami2004.internationalaidanddevelopment|url-status=live}}</ref>

== <!--==Legacy== {{Expand section|date=September 2024}} The 2004 disaster prompted the creation of the [[Indian Ocean Tsunami Warning System]].-->  In popular culture ==

===Film and television===
* ''Children of Tsunami: No More Tears'' (2005), a 24-minute documentary
* ''The Wave That Shook the World'' (2005), educational television series documentary about the tsunami
* ''[[Tsunami: The Aftermath]]'' (2006), a two-part television miniseries about its aftermath
* ''[[Dasavathaaram]]'' (2008), a Tamil thriller film involving the tsunami
* ''Tsunami: Caught on Camera'' (2009), a TV documentary showcasing the tsunami through amateur video with survivor interviews<ref>{{Cite web|url=https://www.digitalspy.com/tv/a193489/24-million-tune-in-for-tsunami-footage/|title=2.4 million tune in for tsunami footage|website=Digital Spy|date=3 January 2010}}</ref><ref>{{Cite news|url=https://www.thetimes.com/culture/tv-radio/article/the-turn-of-the-screw-three-men-go-to-ireland-tsunami-caught-on-camera-piers-morgans-review-of-the-year2009-unwrapped-with-miranda-hart-rwkkqxdwmct?region=global|title=The Turn of the Screw; Three Men Go to Ireland; Tsunami: Caught On Camera; Piers Morgan's Review of the Year/2009 Unwrapped with Miranda Hart|newspaper=The Times|date=19 December 2009}}</ref>
* ''[[Hereafter (film)|Hereafter]]'' (2010), a main character's life is affected after surviving the tsunami while on vacation
* ''[[Hafalan Shalat Delisa]]'' (2011), an Indonesian movie with the tsunami as the initial incident
* ''[[The Impossible (2012 film)|The Impossible]]'' (2012), an English-language Spanish film based on the story of [[María Belón]] and her family
* ''[[Kayal (film)|Kayal]]'' (2014), a Tamil drama film which culminates with the tsunami
* ''Tsunami: Race Against Time'' (2024), a 20-year retrospective that chronicles some of the stories of individual heroism and tragedy<ref>{{Cite AV media |url=https://www.youtube.com/watch?v=DXTK49k3fWo |title=Tsunami: Race Against Time (Full Episode) {{!}} The Big One {{!}} National Geographic |date=2024-11-25 |last=National Geographic |access-date=2025-01-04 |via=YouTube}}</ref>

===Literature===
* ''Paint the Sky with Stars: Selected Poetry in Remembrance of the Boxing Day Tsunami 2004'' (2005) edited by [[Stephen Robert Kuta]]<ref>{{Cite book|url=https://books.google.com/books?id=l21lDwAAQBAJ&pg=PP5|title=Paint the sky with Stars|last=Kuta|first=Stephen|publisher=Re-invention UK|year=2005|isbn=978-0-9549899-0-3|location=Rayne, Essex, England|access-date=16 October 2019|archive-date=24 July 2020|archive-url=https://web.archive.org/web/20200724140700/https://books.google.com/books?id=l21lDwAAQBAJ&pg=PP5|url-status=live}}</ref>
* ''The Killing Sea'' (2006), two teenagers struggle to survive in the days after the tsunami<ref>{{Cite web|date=1 December 2006|title=Book Review: The Killing Sea by Richard Lewis|url=https://www.thetcj.org/books/book-review-the-killing-sea-by-richard-lewis|access-date=15 December 2020|website=The Therapeutic Care Journal|archive-date=26 January 2021|archive-url=https://web.archive.org/web/20210126034824/https://www.thetcj.org/books/book-review-the-killing-sea-by-richard-lewis|url-status=live}}</ref>
* ''[[Wave (Deraniyagala book)|Wave]]'' (2013), a memoir by [[Sonali Deraniyagala]]
* ''On the Island'' (2012), two people stranded on a Maldives uninhabited island are rescued because of the tsunami.

===Music===
* "12/26" by [[Kimya Dawson]], about the event and the humanitarian efforts, from the perspective of a victim whose family died in the disaster.
* "Where the Wave Broke" by [[Burst (band)|Burst]], written in memory of [[Mieszko Talarczyk]], frontman of Swedish grindcore band [[Nasum]] (whom Burst bassist Jesper Liveröd also performed with), who died in the disaster, which led to Nasum's subsequent disbandment.

==See also==
{{Portal|Asia|Indonesia|Sri Lanka|Thailand|India|Malaysia|Maldives|Myanmar|Somalia|Earth sciences|2000s}}
* [[Deaths in December 2004#26|Deaths in December 2004]] – notable people killed in the 2004 Indian Ocean tsunami
* [[List of earthquakes in 2004]]
* [[List of earthquakes in Indonesia]]
* [[List of natural disasters by death toll]]
* [[Lists of earthquakes]]
* [[List of megathrust earthquakes]]

==Notes==
{{Notelist}}

==References==
{{Reflist|refs=
<ref name="AsiaNews-Myanmar">{{cite web|title=Myanmar is withholding true casualties figures, says Thai priest|date=4 January 2005|quote=A missioner in Ranong, a town on the border between Thailand and Myanmar, says locals talk about 600 victims. Burmese political dissidents say the same.|publisher=AsiaNews.it|url=http://www.asianews.it/view.php?l=en&art=2255|access-date=12 February 2011|archive-url=https://web.archive.org/web/20061009053106/http://www.asianews.it/view.php?l=en&art=2255|archive-date=9 October 2006}}</ref>
}}

==External links==
{{Sister project links|auto=1|s=2004 Indian Ocean tsunami bulletins}}
{{Scholia|topic}}
* {{ReliefWeb-link|ts-2004-000147-idn}}
* [http://www.iris.iris.edu/sumatra/ The Sumatra-Andaman Islands Earthquake]. {{Webarchive|url=https://web.archive.org/web/20151021100354/http://www.iris.iris.edu/sumatra/ |date=21 October 2015 }}&nbsp;– [[IRIS Consortium]].
* [https://web.archive.org/web/20070121074902/http://asc-india.org/lib/20041226-sumatra.htm M9.1 Sumatra-Andaman Earthquake & Tsunami, 2004]&nbsp;– Amateur Seismic Centre (ASC) (archived 21 January 2007)
* [http://www.zoriah.net/blog/2008/12/asian-tsunami-anniversary-thailand-tsunami-then-and-now-comparison-series.html Asian Tsunami Anniversary – Thailand Tsunami Then and Now Comparison Series]&nbsp;– [[Zoriah Miller]]
* {{YouTube|id=2ozmwEBOmJo|title=Compilation of videos that show the moment the quake and the subsequent tsunami hit}}
* {{EQ-isc-link|7453151}}

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[[Category:2004 Indian Ocean earthquake and tsunami| ]]
[[Category:2000s in Andhra Pradesh]]
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[[Category:December 2004 in Asia]]
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[[Category:History of Southeast Asia]]
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[[Category:Megathrust earthquakes in India]]
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