Semisopochnoi Volcano
Updated: Apr 19, 2024 09:27 GMT -
Stratovolcano 1221 m / 4,006 ft
United States, Aleutian Islands, 51.93°N / 179.58°E
Current status: normal or dormant (1 out of 5)
United States, Aleutian Islands, 51.93°N / 179.58°E
Current status: normal or dormant (1 out of 5)
Last update: 9 Aug 2023 (Smithsonian / USGS Weekly Volcanic Activity Report)
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Semisopochnoi volcano eruptions: 2021, 2020, 2019, 2018, 1987
Latest nearby earthquakes
| Time | Mag. / Depth | Distance / Location | |||
| Apr 18, 01:06 pm (GMT -9) | 1.6 13 km | 19 km (12 mi) to the S |  261 km W of Adak, Alaska | Info | |
| Saturday, April 13, 2024 GMT (1 quake) | |||||
| Apr 13, 10:41 am (Adak) | 1.1 7.5 km | 2.6 km (1.6 mi) to the NW | 261 km W of Adak, Alaska | Info | |
| Friday, April 5, 2024 GMT (1 quake) | |||||
| Apr 5, 01:04 pm (Adak) | 1.3 15 km | 5.9 km (3.7 mi) to the E | 255 km W of Adak, Alaska | Info | |
| Wednesday, April 17, 2024 GMT (3 quakes) | |||||
| Apr 17, 01:27 am (Adak) | 0.6 7.9 km | 5.8 km (3.6 mi) to the SE | 256 km W of Adak, Alaska | Info | |
| Apr 16, 04:49 pm (Adak) | 0.6 7.1 km | 10.8 km (6.7 mi) to the E | 249 km W of Adak, Alaska | Info | |
| Apr 17, 03:37 am (Adak) | 0.5 6.7 km | 5.9 km (3.7 mi) to the S | 259 km W of Adak, Alaska | Info | |
Background
Semisopochnoi, the largest subaerial volcano of the western Aleutians, is 20 km wide at sea level and contains an 8-km-wide caldera. It formed as a result of collapse of a low-angle, dominantly basaltic volcano following the eruption of a large volume of dacitic pumice. The high point of the island is 1221-m-high Anvil Peak, a double-peaked late-Pleistocene cone that forms much of the island's northern part. The three-peaked 774-m-high Mount Cerberus volcano was constructed during the Holocene within the caldera. Each of the peaks contains a summit crater; lava flows on the northern flank of Cerberus appear younger than those on the southern side. Other post-caldera volcanoes include the symmetrical 855-m-high Sugarloaf Peak SSE of the caldera and Lakeshore Cone, a small cinder cone at the edge of Fenner Lake in the NE part of the caldera. Most documented historical eruptions have originated from Cerberus, although Coats (1950) considered that both Sugarloaf and Lakeshore Cone within the caldera could have been active during historical time.---
Smithsonian / GVP volcano information
Latest satellite images
