Great Sitkin volcano

Stratovolcano 1740+ m / 5,709 ft
United States, Aleutian Islands, 52.08°N / -176.13°W
Current status: erupting (4 out of 5)
Last update: 13 Sep 2021 (eruption continues with new lava flow)

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Typical eruption style: unspecified
Great Sitkin volcano eruptions: 2021, 1974

TimeMag. / DepthDistance/Location
Monday, September 20, 2021 07:04 GMT (1 earthquake)
Sep 19, 2021 10:04 pm (GMT -9) (Sep 20, 2021 07:04 GMT)
0.5

1.8 km
4.2 km (2.6 mi)
45 Km NE of Adak, Alaska
Tuesday, September 14, 2021 07:47 GMT (2 earthquakes)
Sep 13, 2021 10:47 pm (GMT -9) (Sep 14, 2021 07:47 GMT)
0.7

3.2 km
9.3 km (5.8 mi)
48 Km ENE of Adak, Alaska
Sep 13, 2021 6:25 pm (GMT -9) (Sep 14, 2021 03:25 GMT)
0.7

2.5 km
8.2 km (5.1 mi)
47 Km ENE of Adak, Alaska
Monday, September 13, 2021 05:05 GMT (2 earthquakes)
Sep 12, 2021 8:05 pm (GMT -9) (Sep 13, 2021 05:05 GMT)
0.5

6.3 km
3 km (1.9 mi)
40 Km ENE of Adak, Alaska
Sep 12, 2021 8:00 pm (GMT -9) (Sep 13, 2021 05:00 GMT)
0.5

5.1 km
1.8 km (1.1 mi)
41 Km ENE of Adak, Alaska

Background

Constructed within the caldera of an older shield volcano forming the northern half of Great Sitkin Island, 1740-m-high Great Sitkin volcano contains a small, 0.8 x 1.2 km ice-filled summit caldera. Deep glacial valleys radiate from the summit, which lies at the eastern rim of the caldera, which was formed by massive edifice failure that produced a submarine debris avalanche that traveled more than 40 km to the north. The entire island is blanketed with a light-brown to black pumice layer up to 6 m thick. This deposit is overlain over much of the NW side of the island by ash deposits from a subsidiary vent NW of the caldera. Hot springs, mud pots, and fumaroles occur near the head of Big Fox Creek, south of the volcano. Historical eruptions have been recorded since the late-19th century. In 1945, a 400-600 m wide, flat-topped lava dome was emplaced through a glacier filling the steep-sided, 180-m-deep summit caldera.
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Smithsonian / GVP volcano information


See also: Sentinel hub | Landsat 8
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