View source for Talk:Moment magnitude scale

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== Re contested contribution ==

Dr. Ampuero: I thank you for your interest in contributing, and please convey my thanks to Dr. Heaton for his interest. However, Wikipedia is not entirely free-form in how we go about matters; there are certain policies and processes we need to conform to. These are often a bit clunky (which is to say, not yet perfect), but that is how things are. If you won't mind, I would like to offer some guidance that will make the process of contributing easier.

Please note that First and foremost is the policy of [[WP:verifiability|] (often referred to as [[WP:V]]). Basically it means that all content is based on reliable, ''published'' sources, and must be cited to those sources. Even if Dr. Heaton personally wrote and signed the material you added, that is not adequate: it has to be attributed to a verifiable source. (I note that this material does contain citations, albeit incomplete. Those are fixable, so not really at issue.)

But if the text you added is verbatim from a source, then, as Jasper Deng noted in his edit summary, there is a possible copyright issue. This may require some discussion.

I point out that while "boldness" in editing is encouraged, reversion should also be respected. In particular, immediately restoring your material is improper. (See [[WP:BRD]] for an explanation.) So please understand that my undoing of your edit should not be taken as lack of appreciation, but that there are some issues that need to be resolved. Particularly: is the material you added verbatim from a soucrce? And if so, what source? ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 21:15, 6 August 2017 (UTC)

:Dear J. Johnson: Thank you for the much needed explanation of the process. The text I added was written by Prof. Heaton after a coffee hour discussion we had at the Caltech Seismolab, together with Prof. Kanamori, in 2015. Prof. Kanamori, now retired, was one of the authors of the scientific article that defines the moment magnitude scale. The three of us are colleagues at the Caltech Seismolab, the place where the magnitude scales originated, including Richter's. A result of that discussion was the idea to improve the Wikipedia pages on moment magnitude scale and seismic moment. Prof. Heaton emailed me this text circa 03/23/2015, asking me to incorporate it in Wikipedia. He is fully aware that the text can be modified (and hopefully improved) by the community. I wrote "verbatim" in my edit summary just to record that this is really a contribution to Wikipedia by Prof. Heaton. Please let me know how to proceed now. [[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 22:23, 6 August 2017 (UTC)

:I made other edits to the article today, some are substantial and intended to fix common misconceptions. Hopefully it is more clear now how my edits you deleted last night will fit with the rest of the article. I intend to polish the whole if you restore my edits. [[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 03:50, 7 August 2017 (UTC)

::Wow! Look at the that guy go!!  

::You're getting ahead of me. In particular, I can't restore your earlier edits without losing the subsequent edits. It's probably easiest and best to just proceed from where we are at. The important thing is that what ever you add (aside from short quotes) is ''not'' verbatim text of anything that has been published anywhere else; that would raise a copyright issue. If someone advises you on what to add, no problem, but note that you are responsible for whatever you add.

::All (essentially) needs to be attributed to a source. I see you are adding sources, but there are some details that need work. As the previous "style" of citation used here wasn't so great I am going to just run through and switch every thing to a better style. The main points are that all the sources will have full citations in the "Sources" section, done up in templates, and "in-line" cites will be "short-cites". Well, as I find time to do that.

::One point of contention: isn't M<sub>L</sub> still determined in many places? On that basis shouldn't the section header refer to "Richter scale" not as a "former scale", but the "original scale"? ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 07:49, 7 August 2017 (UTC)

:::Yes, M<sub>L</sub> is used everywhere for small earthquakes, because seismic moment (the quantity needed to compute M<sub>w</sub>) cannot be measured if the earthquake is too small and waves are too attenuated. So I agree the header should read "original scale". Perhaps the view that Richter's scale is obsolete comes from the fact that M<sub>w</sub> supersedes M<sub>L</sub> for large earthquakes and by design matches M<sub>L</sub> for moderate-size earthquakes. That covers most earthquakes that matter to the public in highly seismic places (like California). However, the small earthquakes, for which we can't measure M<sub>w</sub>, are of public concern in places that are not traditionally exposed to earthquakes. These include regions that have been recently exposed to anthropogenic seismicity induced by gas production, waste water disposal, etc, where houses were not built with earthquakes in mind. I may add somewhere a note about the use of M<sub>L</sub> after adding more explanation about how seismic moment is measured/estimated. [[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 09:04, 7 August 2017 (UTC)

::::My understanding (for what all it's worth) is that M<sub>w</sub> is now the ''standard'' scale (in part because it is derivable from physical parameters), and the ''preferred'' scale for events over ~ M 5 (because it is non-saturating). I don't see "{{tq|not traditionally }}[historically?]{{tq| exposed to earthquakes}}" as significant; but perhaps ML is more significant for small "local" (i.e., non-teleseismic) quakes that might not register out of the area? I have also seen comments that ML is faster, easier to calculate (for a preliminary determination), but is that still a factor, given all the fancy software available nowadays?

::::Other questions come to mind in connection with the magnitude template I'm working on; I'll ping you from there later on. Right now I'm going to work on the citations. ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 20:18, 7 August 2017 (UTC)

::::{{ping|Ampuero}} You just trashed some complicated edits I was doing. Please back-off until I give an all-clear. ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 21:30, 7 August 2017 (UTC)

:::::Sorry about that newbie mistake, I did not realize you were working on it.  [[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 21:43, 7 August 2017 (UTC)

:::::My speculation about why someone would write "former scale" (which I interpreted as meaning "obsolete scale") comes from seeing seismologists frustrated with the habit of media reporters to call all magnitudes Richter (as noted at the end of the intro of this wiki article). The official earthquake catalogs of the Southern California Seismic Network use Richter ML for M<4ish. Otherwise we use Mw. That is what "preferred" means: we use it when possible. But reporters in California never report about small M<4 earthquakes, so they are never accurate to report the official magnitude as Richter magnitude. However, in Groningen, The Netherlands, the public can make a big deal of a M3ish earthquake and Dutch reporters are very likely correct to report its M as a Richter magnitude. It would be less confusing if reporters just dropped the "on Richter's scale", but they have their own ways. A reporter / science writer's perspective here: https://www.geolsoc.org.uk/Geoscientist/Archive/June-2007/Off-the-Scale . See also this twitter thread: https://twitter.com/seismo_steve/status/893862117136269312 [[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 22:08, 7 August 2017 (UTC)

::::::I suspect "former" was (vaguely subconciously?) meant in respect of former ''status'' as the standard scale. At any rate, the point about "M" no longer being de facto "Richter" is made at several articles, so eventually it will become general knowledge. One small problem is that the USGG website that used to explain this (see the notes) was removed when the USGS did their big <expletive>, <expletive> website revamp.

::::::I am done for now (the "in-use" tag is removed); won't get to the other questions till tonight at the earliest. You might notice: 1) use of {citation} templates instead of {cite}; 2) full citations in text moved to "Sources" and 3) replaced with short-cites ({Harv} templates). Still more cleanup needed. More on this later. ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 23:36, 7 August 2017 (UTC)

::::::You might also notice that I generally have "p=" in my short-cites. It's reminder to editors that we really should have the "in-source specifier" – usually the page number — showing where the material is taken from. If you have any those specifics it would be good to add them. (They are expected for a "Good Article" rating, which I think this could shape up to.) 

::::::Thanks for adding Thatcher & Hanks. (I had it, then it disappeared. And most suspiciously, Hanks & Kanamori showed up doubled.Hmm.) I also found a detailed citation for Kostrov, 1977. But if you have a copy of it available you might want to check it. I also took out the inconsequential "Magnitude and Intensity" section; I think it is better handled at at [[Seismic scale#Earthquake magnitude and ground-shaking intensity]]. ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 04:43, 8 August 2017 (UTC)

::::::Just happened to click on your twitter url, and ... there's something ironic: the "Daily Mail" finally gets something right, but it's essentially banned from Wikipedia. ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 04:48, 8 August 2017 (UTC)

== "Nuclear explosions"? ==

Should the "Nuclear explosions" section be deleted?

While readers might be interested in the seismic equivalent of a nuclear explosion, the essence of the matter is, as stated: "{{tq|Such comparison figures are not very meaningful.}}" But [https://en.wikipedia.org/w/index.php?title=Moment_magnitude_scale&oldid=794630919 as currently written] the section gets there in rather round-about way, with a lot more detail than is necessary. Even worse, that section is effectively unsourced: the first note is from a Congressional report with no sources, and no attribution, and fails as a reliable source; the other two sources are 404 urls.

As this article has been written at technical level, it should have primary and secondary sources (perhaps textbooks), not blogs. And regardless of the level of the intended audience, it is probably sufficient to explain why the comparison is not meaningful, rather than work out a result only to throw it away.

I am inclined towards deletion. Comments? ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 22:05, 9 August 2017 (UTC)

:I will ask colleagues in this sub-field of Seismology if they care about this section and can improve it. [[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 01:39, 11 August 2017 (UTC)

::Quite aside from poor structure and inadequate citation, I doubt that such a section is really germane. If someone wanted to know how a nuclear blast compares with an earthquake, ''perhaps'' that could be addressed at [[seismic moment]]. But I don't see it as being significant for moment magnitude scale. ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 23:14, 11 August 2017 (UTC)

== Formatting markup ==

In this article formulas are displayed using the &lt;math> tag, which generates large and bolded LaTex output. For formulas on their own line this is standard and acceptable. However, the same markup has also been used in the text for the sole purpose of formatting the several magnitude scales. That is an ''undesirable'' use, as the large and bolded result (e.g.: <math>M_w</math>) is '''TOO LOUD''', and rather intimidating. It is also ''unnecessary'', as the {{tl|M}} template is now available that provides a more reasonable result.  (And is easier to use, and provides other features including more consistent use across the encyclopedia.) I am therefore replacing in-line instances of <code><math>M_w</math></code> (and similar instances) with <code>{{m|w}}</code>. ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 22:55, 9 August 2017 (UTC)

== Mw comparisons. Need a good chart. ==

I am going to remove the table under [[Moment_magnitude_scale#Comparison with Richter scale]]. It is not well done, does not provide a good sense of how {{m|w}} relates to {{M|L}} (or any other scale), it's just so much clutter.

What we need is a well-done graph, such as Utsu's 2002 figure 1, showing "Relationship between magnitude scales" (seen [https://books.google.com/books?id=BHgOwNCGbnAC&pg=PA212&lpg=PA212 here] as figure 7). Or even Kanamori's (1983) figure 4b. But both of those are copyrighted. Maybe someone knows how to create a similar chart? ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 23:01, 16 August 2017 (UTC)

{{ping|Ampuero}} With all that high-grade talent you hang out with, is there any chance you could get someone to contribute a publication grade graph showing the interrelation of the several scales? Some good ones have been done, but the main problem is getting one that the creator (or copyright owner) will grant copyright permission. ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 08:12, 12 September 2017 (UTC)

: There is not enough information in Utsu (2002) to reproduce his figure conveniently: no equations are given for the curves; the method may be explained in more detail in Utsu (1982) but in Japanese. Fig 4 in Kanamori (1983) is basically a hand drawn sketch from his fig 1. You could try to do the same. These relations between magnitudes are not commonly used by seismologists. We rarely try to convert from one magnitude to another (there are exception of course, like [http://bssa.geoscienceworld.org/content/107/1/85 this] one from my own work). The different magnitude scales measure different aspects of an earthquake, hence such conversions have a large scatter and using them can lead to loss of information. [[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 03:07, 19 September 2017 (UTC)

::Thanks. I understand about about the doubtfulness of intermagnitude conversions, but was thinking such a graph might convey to non-experts how the scales diverge. Oh, well. ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 04:13, 19 September 2017 (UTC)

:::You can use figure 6 of Heaton, T.H., Tajima. F., and Mori, A.W., 1986, Estimating ground motions using recorded accelerograms, Surveys in Geophysics, V. 8, pp 25-83 [http://www.ecf.caltech.edu/heaton/papers/Estimating%20Ground%20Motions.pdf PDF]. Tom Heaton wrote to me "I was usgs and thus there is no copyright on this figure. This figure was used by many and often without even a reference." [[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 06:58, 26 September 2017 (UTC)

:::Hey, that will be great. I was looking at another version of that figure, but didn't know if that came under the government exemption. I'll see about grabbing it, but probably won't get to it till after GSA. And of course I'll see that there is credit. ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 21:40, 26 September 2017 (UTC)

:::I noticed a figure has been added, but its attribution (a URL linking to US Dept of Transportation) seems incorrect. It looks a lot like fig 6 of Heaton et al (1986 [https://www.researchgate.net/publication/226448629_Estimating_ground_motions_using_recorded_accelerograms PDF]).[[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 11:28, 28 March 2019 (UTC)

::::Hi Pablo! Good to hear from you. I have been formulating some questions for you; perhaps tomorrow.
::::Yes, the key part of that diagram ([[:File:Moment_Magnitude.gif]]), the data lines, are identical to Fig. 6; someone has merely added the grid and replaced the annotations. (I thought it looked familiar.) And the documentation on WikiCommons is quite deficient. (No creator given, the url does not show that figure, etc.) So: possible copyright violation. I have run out of time for today, but I'll look into this tomorrow. &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 23:50, 28 March 2019 (UTC)

::::There some sticky issues with that file, so I have asked for advice. For starters, that image isn't really figure 6, it's a look-alike that copied in the data curves of figure 6. Whether that would be a copyright violation I don't know, but if Tom objected I can have the image here "speedily deleted". 
::::As to retaining it: as far as I can tell Tom and his coauthors are the creators, but it is not clear if he produced it as a USGS employee. And I don't know how the non-federal status of the coauthors affects this. If Tom has the original graph (from which the published version was derived) and wanted to contribute it, I could make a replacement file. Perhaps you could check with him about this? &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 23:27, 29 March 2019 (UTC)

::::Never mind! The source of this file is doubtful (likely Kanamori's), and the essential elements may be under copyright. I have removed it from this article, and it is subject to deletion from WikiCommons. I have in mind a better figure, but don't currently have the time to pick out the data. &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 22:03, 31 March 2019 (UTC)

== Remove "Nuclear explosions" section? ==

I propose removal of the [[Moment magnitude scale#Nuclear explosions]] section. I would argue that nuclear (or any other kind of) explosions and earthquakes are not directly comparable, and attempting to do so (without more explanation than is suitable here) is misleading. ''Distinguishing'' between explosions and quakes is certainly notable, but more for seismology generally; it has nothing to do with this scale. ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 22:10, 13 November 2017 (UTC)

:I second your proposal. [[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 08:02, 14 March 2018 (UTC)

:Agree that this should be done. [[User:Mikenorton|Mikenorton]] ([[User talk:Mikenorton|talk]]) 10:09, 14 March 2018 (UTC)

::Done! ~ [[User:J. Johnson|J.&nbsp;Johnson (JJ)]] ([[User_talk:J. Johnson#top|talk]]) 20:09, 14 March 2018 (UTC)

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== On citing equations ==

Regarding a recent edit summary by {{ping|Ampuero}} Actually, we ''do'' need to cite where equations come from. They are (essentially) being quoted, and per our core content policy [[WP:Verifiability]]: "{{tq|quotations and any material challenged or likely to be challenged must be supported by inline citations.}}" Sure, this is often scamped, but ''continuance'' of a bad habit should not be taken as ''justification''. 

Proper citation is essential for verification, especially when there are (as we have been having) little spats as to the correct details. Resolution of such matters is generally by getting everyone's eyeballs on the same source.  This should be cited immediately adjacent to the equation (not just casually mentioned somewhere in the text). And we really should have an in-source specification such as a page number, else we can't find the equation or formula cited, or (even worse) we find a slightly different formula.  (Incidentally: the "named-ref" construction does not allow in-source specification; please use {{tl|harv}} templates instead.)

As to the case at hand, the text in the "Definition" section is currently: 
{{talkquote |
:The moment magnitude M{{sub|w}} is a dimensionless value defined by Hiroo Kanamori{{dummy ref|12}} as 

::{{math|{{mvar|M{{ssub|w}}}} {{=}} {{sfrac|2|3}} log{{ssub|10}} {{mvar|M{{ssub|0}}}} 10.7}},

:where {{M|0}} is the seismic moment in dyne⋅cm ({{e|7}} N⋅m).{{dummy ref|1}}
}}

Note [12] is to Kanmori 1977, but '''without any page or equation numbers'''. The problem is: ''that formula does not appear in Kanamori 1977''. It appears in Kanamori 1978 (but not cited here), and in Hanks & Kanamori 1979 (note [1]) but again '''without page or equation numbers'''. Which MAKES ALL OF THIS REALLY HARD TO VERIFY!

So we need to not only cite equations (or rather, their source), but also consider their ''placement'' (unambiguously associated with the equation) and specification (page number and, ideally, equation number). 

There is also the matter of: ''which source'' to use. E.g., can anyone explain why credit for devising the moment magnitude scale is usually given to Kanamori <s>1978</s> 1977 (his JGR article), which doesn't carry his work through to the actual formula, but not to his 1978 article in ''Nature'', which shows the formula?

Similarly: why do modern sources credit Hanks & Kanamori 1979 with the coefficient of {{tq|16.05}}, though that value appears no where in that paper?  (See also Tom Heaton's six-year old comment [[Talk:Moment magnitude scale/Archive 1#Mw is not moment magnitude|here]].)

I am putting together a table with my best representation of the Mw formula in various sources so that as we sort through this we can be better assured we're all looking at the same item. When I am done other editors should double-check these against the originals. &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 00:40, 16 January 2019 (UTC)

:The formula doesn't appear in Kanamori 1977 but he does describe exactly how to make it, without actually writing down the result. Once you have his equation 4' and combine it with the Gutenberg-Richter relation (in the way that he describes) you have the formula. Hanks and Kanamori reference the 1977 paper for the derivation. We could perhaps for completeness cite both the 1977 and 1978 papers. [[User:Mikenorton|Mikenorton]] ([[User talk:Mikenorton|talk]]) 15:28, 16 January 2019 (UTC)
:You refer to a Kanamori JGR paper in 1978 - I'm not seeing it, what's its title? [[User:Mikenorton|Mikenorton]] ([[User talk:Mikenorton|talk]]) 15:28, 16 January 2019 (UTC)
::Sorry; the JGR paper is 1977. Citations in the [[Moment magnitude scale|article]].
::I understand that Kanamori is credited with working out how to do the calculations in 1977, and even actually doing them, but the plain fact is he did not explicitly present the formula until 1978. In a WP perspective, doing the derivation would be [[WP:OR]], not, I think, a "routine calculation" covered by [[WP:CALC]]. For purposes of verification we could cite some else as crediting the ''formula'' to "Kanamori 1977" (just as we could cite someone else for crediting the 16.05 coefficient to Hanks and Kanamori 1979), but citing the putative source directly clearly fails verification. Accurate presentation of these matters requires some care. &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 21:34, 16 January 2019 (UTC)

:I would replace that particular reference by Kanamori (Nature 1978), which is the first publication where the equation appears in that particular form.[[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 13:15, 28 March 2019 (UTC)

== Table of Mw formula variants ==

Best representations of Mw formula variants from different sources. These should be double-checked. &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 00:50, 16 January 2019 (UTC)

{| class=wikitable
|- --
! Source
! {{mvar|M{{ssub|0}}}} in dyne-cm (CGS)
! {{mvar|M{{ssub|0}}}} in Newton*m (SI)

|- --
| Kanamori 1978:
| {{math|M{{ssub|w}} {{=}} (log M{{ssub|0}}/1.5) – 10.7}}
|

|- --
| Hanks & Kanamori 1979, Eq. (7):
| {{math|'''M''' {{=}} {{sfrac|2|3}} log {{mvar|M{{ssub|0}}}} – 10.7}}
|

|- --
| IASPEI IS 3.3, p11:
| {{math|Mw {{=}} (log{{ssub|10}}M{{ssub|0}} – 16.1)/1.5}}
| {{math|Mw {{=}} (log{{ssub|10}}M{{ssub|0}} – 9.1)/1.5}}

|}
:The bottom two are swapped (using [http://iaspei.org/_Resources/Persistent/3de00aeb67e3ff2e6e78472357cd2899c633edea/Summary_WG_recommendations_20130327.pdf this IASPEI source] for equations 7a & 7b), but otherwise all checks out. [[User:Mikenorton|Mikenorton]] ([[User talk:Mikenorton|talk]]) 15:03, 16 January 2019 (UTC)
::Yes, you're right. (That's why we check!) And I just unswitched them (SI gets the 9.1). Incidentally, what you cited is the 2013 Summary of the WG's recommendations, what I cited is the 2014 Information Sheet 3.3 ("The new IASPEI standards ..."). Which (except for the equation numbers) have identical wording. &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 20:47, 16 January 2019 (UTC)

== &lt;math> or {{tl|math}}? ==
While trying to display the Hanks & Kanamori 1979 equation 7 (above) in &lt;math> I have difficulty rendering their bold, non-italic "'''M'''". Perhaps someone could explain how to do that, but I got wondering (again): (a) Do we have to use &lt;math>? (b) Is it really useful to display equations so <math>BIG and BOLD</math>? E.g., I am a lot less intimidated by math equations than the most readers, yet even I have often felt put off by Wikipedia pages with such powerful expositions of <math>Math</math> (rendered in &lt;math>!). As an alternative, it seems to me that for most cases {{tl|math}} is easier to use and displays just as well. Examples:
  
:(1){{nbsp|3}} <math> M = {\frac{2}{3}}\log M_0 - 10.7</math>
:(2){{nbsp|3}} <big>{{math|'''M''' {{=}} {{sfrac|2|3}} log ''M''{{ssub|0}} – 10.7}} </big>
:(3){{nbsp|3}} {{math|'''M''' {{=}} {{sfrac|2|3}} log ''M''{{ssub|0}} – 10.7}}

(1) is in standard &lt;math> markup, with the incorrectly italicized '''M''', and ''everything'' is bolded. (2) is in {math} markup, with a correct M, and a tad less bolding. This is also wrapped in &lt;big> to make it the same size as (1). (3) is normal size {math} markup, and a lot less intimidating. And the most accurate representation of the original equation.

Wouldn't the less intimidating {math} format be better? &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 00:03, 18 January 2019 (UTC)

:It's not something that bothers me too much personally, but I think that the {math} markup is probably better. [[User:Mikenorton|Mikenorton]] ([[User talk:Mikenorton|talk]]) 00:31, 19 January 2019 (UTC)

::It seems to have been an issue years ago at MOS, though I have yet to dig through all that. As no one has objected, I have started replacing formulas here with {math} renditions, though I'll wrap them in &lt;big> for now so there is less dissonance. For a while we will have both forms in this article, which might be useful for comparison. &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 23:39, 19 January 2019 (UTC)

== Lead section ==

I am trying to work up a better lead section, but having a little difficulty pulling together anything entirely satisfying; would be interested in comments on the following candidate. &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 00:53, 23 February 2019 (UTC)

{{talkquote|The '''moment magnitude scale''' ('''MMS'''; denoted '''''M''{{sub|w}}''' or '''''M''''') is a measure of the magnitude ("size") of an earthquake based on its [[seismic moment]] (or ''[[work (physics)|work]]'' done in producing the earthquake) expressed in terms of the familiar magnitudes of the original [[Richter magnitude scale|magnitude scale]] developed by [[Charles F.  Richter]].}}

:My only concern is that seismic moment is not really the "work done in producing the earthquake". This is a usual confusion stemming from at least two reasons:
:1. Units: The units of moment are N.m, the same units as work and energy. But seismic moment is actually the torque (also in N.m) of each of the two force-couples in the double-couple representation of an earthquake. This is somewhat clarified [https://en.wikipedia.org/wiki/Moment_magnitude_scale#Seismic_moment later in the article], in a brief note within brackets, but it would be useful to avoid perpetuating the confusion between work and torque in other parts of the article. 
:2. History: The initial intent of the moment magnitude was really to measure radiated energy, but the quantity used for practical purposes (seismic moment) was actually a measure of something else. This is, I hope, sufficiently described in the [https://en.wikipedia.org/wiki/Moment_magnitude_scale#Introduction_of_an_energy-motivated_magnitude_Mw historical section of the article] and in the [https://en.wikipedia.org/wiki/Moment_magnitude_scale#Relations_between_seismic_moment,_potential_energy_released_and_radiated_energy section about energy]. The issue is also being pointed out in the literature, e.g. [https://doi.org/10.1007/s00024-018-1994-7 Okal 2019]: "we stress the significant scientific value of reporting radiated seismic energy independently of seismic moment (or of reporting several types of magnitude), in order to fully document the rich diversity of seismic sources" (that paper dives deeply into the history and pitfalls of the empirical relation between magnitude and energy developed by Gutenberg and Richter, which was a (imperfect) building block in the development of the moment magnitude scale).
:I do realize the lead section should be accesible to a broad audience and the relation to torque cannot be grasped before understanding the concept of double-couple. For the sake of accuracy, I would remove the note about "work" in the lead section and other sections. [[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 09:05, 15 September 2019 (UTC)

::Hi Ampuero, it's nice to hear from you. From my studies earlier this year I think I have a better grasp of what you are talking about. And I would love it if we could work out a way of explaining that so most readers would understand it. Unfortunately I'm currently pretty much fully engaged on some other work that has a stronger claim to importance and priority, so it will likely be a couple of months before I can get back here. But I am looking forward to it. &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 19:45, 18 September 2019 (UTC)

:::Consistently with section [[Moment_magnitude_scale#Relations_between_seismic_moment,_potential_energy_released_and_radiated_energy section about energy|Relations between seismic moment, potential energy released and radiated energy]], I suggest we remove "(a measure of the work done by the earthquake)" from the lead section. Moreover, in section [[Moment_magnitude_scale#Seismic_moment|Seismic moment]], I suggest we replace "a measure of the work accomplished by the faulting of an earthquake ..." by "a measure of the fault slip and area involved in the earthquake. Its value is the torque of each of the two force couples that form the earthquake's equivalent double-couple".[[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 09:26, 25 January 2021 (UTC)

::::Thanks Ampuero, I've made your suggested changes. I wasn't so sure about the paranthetic sentence that followed the second change - is that still helpful? [[User:Mikenorton|Mikenorton]] ([[User talk:Mikenorton|talk]]) 16:09, 3 February 2021 (UTC)

:::::It's useful, but not essential because the interested reader can find that more technical information in [https://en.wikipedia.org/wiki/Seismic_moment the Seismic Moment page] [[User:Ampuero|Ampuero]] ([[User talk:Ampuero|talk]]) 16:23, 3 February 2021 (UTC)

::::::Ok, thanks, I'll leave it be. [[User:Mikenorton|Mikenorton]] ([[User talk:Mikenorton|talk]]) 19:21, 3 February 2021 (UTC)

== Capitalization of "local magnitude scale" ==

[[Wikipedia:Manual of Style/Capital letters#Science and mathematics]] says that scientific terms like "local magnitude scale" are lowercase, unless they are derived from proper nouns. If the convention was to capitalize, it would be "Local Magnitude Scale", but "Local magnitude scale" is a weird combination of the two conventions. -- [[User:Beland|Beland]] ([[User talk:Beland|talk]]) 05:18, 23 December 2019 (UTC)

:The MOS doesn't specifically mention any kind of "magnitude scale". It does mention [[Hermitian matrix]] and [[Lorentz transformation]], which are parallel to this usage. And we do have cases of "G-R magnitude" (Gutenberg-Richter, {{M|gr}}), "Nuttli magnitude" ({{M|N}}), and "JMA magnitude" ({{M|JMA}}). What makes "Local magnitude scale" odd is that the ordinary use of "Local" is not as proper noun. But a problem sometimes arises where "local" is used for a ''local'' (or regional) scale based on the modern {{M|L}} scale and calibrated with local parameters to have comparable results, or for a ''local'' scale that is similar but not so calibrated. The latter are sometimes distinguished with a lower-case letter "l": M{{sub|l}}. So we have we have a special case here, and I think an exception is warranted, so that readers will understand that "Local" is not a generic adjective, but refers to a specific scale.  &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 21:43, 12 January 2020 (UTC)

== Quote marks for "work" and "Richter" ==

Greetings, [[User:J. Johnson|J. Johnson]]! It seems two editors have now changed
:(a measure of the "[[work]]" done by the earthquake)
to
:(a measure of the [[work]] done by the earthquake)

This is not a quotation from any particular source, so quote marks aren't appropriate here. Yes, "work" is being used in a specific technical sense, but adding quote marks is not in general a way in English to indicate technical usage, and the presence of quote marks makes it sound like the article is weirdly skeptical about the concept of work. If it's necessary to explain to readers in what sense the word is meant beyond providing the link, it should be done explicitly. For example:

:(a measure of the [[work]]—[[force]] times distance—done by the earthquake)

-- [[User:Beland|Beland]] ([[User talk:Beland|talk]]) 01:17, 29 December 2019 (UTC)

:I am not disputing that. What I disputed was removing the quotes from "Richter", as I explained in my edit summary. As you don't mention that, I presume we are okay on that point. If you think there should be some support for that in this article, sure, I can add a note, but it might be a bit before I can get to that. &diams;&nbsp;[[User:J. Johnson|J.&nbsp;Johnson&nbsp;(JJ)]] ([[User_talk:J. Johnson#top|talk]]) 00:47, 30 December 2019 (UTC)
::Ah, great. I only asked because you reverted the removal of quote marks from "work" twice, which might not have been intentional. I've removed them again; feel free to add an inline definition if you think it's warranted. -- [[User:Beland|Beland]] ([[User talk:Beland|talk]]) 19:47, 30 December 2019 (UTC)
::I don't think there should be quote marks on "Richter" either; I was just taking issues one at a time. [[Richter magnitude scale]] is the name of the article on the M<sub>L</sub> scale, with no quote marks, and article titles are supposed to be the most common name used by general audiences. In general, quote marks are not used around the inventor of a thing that has been named after them, like we don't say: "Newtonian" physics. Apparently sometimes in less technical contexts the phrase "Richter scale" is applied to scales other than M<sub>L</sub>, possibly including this one. Adding quote marks does not disambiguate which scale is meant by a name which could be interpreted ambiguously; if this is a problem, using an unambiguous name or phrasing can clear it up. The current phrasing here actually doesn't make it clear that the Richter magnitude scale is the same as the  M<sub>L</sub> scale, and the phrase "in terms of" is rather confusing. I'll try a bit of a rewrite. -- [[User:Beland|Beland]] ([[User talk:Beland|talk]]) 19:47, 30 December 2019 (UTC)
:::(FTR, also discussed at [[Talk:Richter magnitude scale#Intro changes]] -- [[User:Beland|Beland]] ([[User talk:Beland|talk]]) 01:48, 6 January 2020 (UTC))

== Logarithms in the formulae should include bases ==

I attempted to calculate the seismic magnitude from the released energy using the following Kanamori's definition  
:<math> M_w = 2/3 \log E_s - 3.2 </math>
Since there was no mention about the log base in the formula, I assumed that the it was '''e''', or Euler's number.  
:<math> M_w = 2/3 \log_{e}(E_s) - 3.2 </math>
However, I found that my calculation results fell many orders of magnitude greater than what other online resources indicated.  
A post in [https://socratic.org/questions/how-much-energy-in-joules-is-released-by-an-earthquake-of-magnitude-8#:~:text=An%20earthquake%20with%20a%20magnitude,e%2B16%20J%20of%20energy. socratic.org] describes the relation between magnitude and energy. It claims that magnitude 8 equqals to 6.309573e+16 joules in energy. When I plug in this number in the formula above, I got 22.588952994535738 as the magnitude.  
I started to speculate that the base should have been 10 instead of e, and sure enough, when I swapped the base to 10, I got 7.999999979589213 as the final magnitude.  
:<math> M_w = 2/3 \log_{10}(E_s) - 3.2 </math>
Since the post on [https://socratic.org/questions/how-much-energy-in-joules-is-released-by-an-earthquake-of-magnitude-8#:~:text=An%20earthquake%20with%20a%20magnitude,e%2B16%20J%20of%20energy. socratic.org] doesn't cite anything, they could also be using a wrong formula, but either way, there should be a clarification on what the base is in all the formulae in the page.  <!-- Template:Unsigned --><span class="autosigned" style="font-size:85%;">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Марсианский|Марсианский]] ([[User talk:Марсианский#top|talk]] • [[Special:Contributions/Марсианский|contribs]]) 07:59, 22 June 2022 (UTC)</span> <!--Autosigned by SineBot-->

== Logarithm of non-dimensionless quantities ==

Please, can we pretend, that not all of us have skipped high school for good, and realise that logarithms of non-dimensionless quantities do not make sense? It is just stupid to write "log(E) = ... (in Joules)", a logarithm of an energy is undefined, basically this amounts to writing nonsense, and adding in brackets an instruction for how to deal with the nonsense. I realise this notation is often used in practice, but slang language is also used in practice yet is avoided on Wikipedia. The proper way would be to make the logarithm argument dimensionless by including the reference quantity there. The given example could be "log(E/1J) = ...". [[User:WikiPidi|WikiPidi]] ([[User talk:WikiPidi|talk]]) 14:02, 14 September 2023 (UTC)

== About this strong earthquake ==

In the 1900's, there was a earthquake with a magnitude of 9.6, destroying almost 90% or earth. But in a earthquake killscreen video, it showed the same amount from in the 1960's (9.6). [[Special:Contributions/2606:A800:C802:3F00:6CB2:5ACB:B316:2092|2606:A800:C802:3F00:6CB2:5ACB:B316:2092]] ([[User talk:2606:A800:C802:3F00:6CB2:5ACB:B316:2092|talk]]) 02:58, 20 May 2025 (UTC)