Bogoslof Island

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Template:Short description Template:Infobox mountain

Bogoslof Island or Agasagook Island (Template:Langx[1]) is the summit of a submarine stratovolcano at the south edge of the Bering Sea, Template:Convert northwest of Unalaska Island of the Aleutian Islands chain. It has a land area of Template:Convert and is uninhabited. It is Template:Convert long and Template:Convert wide, with a peak elevation of Template:Convert. The stratovolcano rises about Template:Convert from the seabed, but the summit is the only part that projects above sea level.[2] The island is believed to be relatively new, with the volcano being entirely below sea level before 1796, and most of the presently 300-acre island being formed by eruptions since 1900.

History

The first known emergence of the island above sea level was recorded during an underwater eruption in 1796. Since then, parts of the island have been successively added and eroded.[3] About Template:Convert northwest of Bogoslof, a small volcanic dome emerged in 1883 from the same stratovolcano and has become a stack rock formation known as Fire Island. On the southwest side of Bogoslof, another dome erupted in 1796; it is now called Castle Rock. Other eruptions have occurred in 1796–1804, 1806–1823, 1883–1895, 1906, 1907, 1909–1910, 1926–1928, 1992, and 2016–2017.[2] The island is a breeding site for seabirds, seals, and sea lions. An estimated 90,000 tufted puffins, guillemots, red-legged kittiwakes and gulls nest here.

In 1909, President Theodore Roosevelt designated Bogoslof Island and Fire Island a sanctuary for sea lions and nesting marine birds. Together, as the Bogoslof Wilderness, they are currently part of the Aleutian Islands unit of the Alaska Maritime National Wildlife Refuge.[4] In November 1967, Bogoslof Island was designated a National Natural Landmark by the National Park Service.[5] The Bogoslof Island group was added to the National Wilderness Preservation System in 1970.

Eruption year Lava dome
1796–1804 Castle Rock
1806–1823 none?
1883–1895 Fire Island
1906–1910 none
1926–1928 unnamed
1992 unnamed
2016–2017 none

2016–2017 Eruptions

File:Boiling Mud Pot on Bogoslof Island by Nora Rojek USFWS.jpg
Boiling mud, August 2018
  • 20 December 2016: A series of short nearly-daily volcanic eruptions started, producing towering volcanic ash clouds and volcanic lightning, changing the geography of the island. As there are no cameras or monitoring stations on the island and the area is usually overcast, details were uncertain. However, when the weather became favorable, it was seen that a small vent slightly offshore of Bogoslof's northeast beach had erupted explosively, fracturing the original island in two, and forming a new, smaller island to the northeast.[6]
  • 25 December 2016: Satellite images of the island showed that the island had fractured into three smaller islands centered on what was thought to be the active vent of the eruption, gaining a net Template:Convert, compared to its previous area of Template:Convert. Bogoslof continued to grow in the following weeks, reaching a size of Template:Convert on January 11, 2017, and merging again into a single island.
  • 02:08 UTC on 20 February (17:08 AKST on 19 February): A significant explosive eruption began at Bogoslof volcano. Seismic and infrasound data showed a series of short-lived explosive pulses through 02:45 UTC; seismicity decreased slightly since then. Recent satellite images show a cloud as high as 25,000 ft asl.[7][8]
  • 11 March 2017: Bogoslof was Template:Convert in size, having more than tripled in size, and forming into a large circular island around the central vent, and would likely continue to grow.
  • 10 May 2017: Bogoslof was estimated to have an area of about 319 acres or 1.3 square kilometers.
  • 17 May 2017: An eruption sent ash 34,000 feet into the atmosphere.[9]
  • 28 May 2017: Another eruption sent ash as high as 35,000 feet and raised Aviation Color Code to red, its highest level. Ash that rises above 20,000 feet is a threat to airliners in the area [10] The National Weather Service Alaska Aviation Weather Unit also issued an alert that the ash cloud may climb as high as 50,000 feet.[9]
  • 30 August 2017: An eruption occurred, with slight volcanic activity continuing into early December, after which the volcano appeared to return to relative inactivity.

Gallery

See also

References

Template:Reflist

External links

Template:Sister project

Template:Islands in the Bering Sea

Template:Authority control

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  10. ↑ Script error: No such module "citation/CS1".
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