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Location:
92 km W of Adak, Alaska
Period:
13 Nov 2022 19:07:15 - 15 Nov 2022 03:04:32 (1 day 7 hours 57 minutes)
Volcanoes in 100km radius:
Takawangha(1km), Tanaga(11km), Bobrof(38km), Gareloi(55km), Kanaga(56km), Moffett(85km)
Earthquakes:
42
12 swarms found nearby.
2006
PS20060708.1(114.1km)
8 Jul
9 hours
10 earthquakes
2008
2 May
10 days 5 hours
184 earthquakes
2017
23 Jan
2 days 23 hours
126 earthquakes
2020
S20200122.2(12.6km)
22 Jan
10 days 13 hours
627 earthquakes
2021
S20210224.2(10.5km)
23 Feb
1 day 16 hours
34 earthquakes
2022
17 Nov
7 days 23 hours
341 earthquakes
12 Dec
10 days 11 hours
186 earthquakes
2023
10 Feb
2 days 6 hours
71 earthquakes
17 Feb
6 days 13 hours
309 earthquakes
28 Feb
1 day 15 hours
114 earthquakes
4 Mar
57 days 17 hours
4231 earthquakes
22 Jun
4 days 21 hours
90 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm VS20221114.1 Near Adak, Alaska

The seismic swarm designated VS20221114.1 occurred 92 km west of Adak, Alaska, in the Andreanof Islands portion of the Aleutian chain. Activity began at 19:07 on 13 November 2022 and concluded at 03:04 on 15 November 2022, spanning 31 hours and 57 minutes. During this interval, 42 earthquakes were recorded.

Magnitudes ranged from 0.2 to 1.8, with the majority of events falling between 0.4 and 1.0. Depths were predominantly shallow, concentrated between 1 km and 6 km, consistent with upper-crustal processes. The largest event reached magnitude 1.8 at a depth of 4 km on 14 November at 20:10. A secondary peak of activity occurred in the late afternoon of 14 November, when multiple events of magnitude 1.2–1.6 clustered within minutes of one another.

This swarm represents the sixth such sequence recorded in the region since 2000. Earlier episodes took place in 2006, 2008, 2017, 2020, and 2021. Each prior swarm was similarly brief and composed of low-magnitude events, indicating a recurrent but localized style of seismicity.

The Andreanof Islands lie within the Aleutian subduction zone, where the Pacific Plate converges with the North American Plate at approximately 7–8 cm per year. This tectonic setting produces the volcanic arc and associated seismicity that characterize the entire Aleutian chain. Shallow crustal swarms in this area are commonly linked to fluid migration or minor stress adjustments along pre-existing faults rather than to the deeper megathrust interface responsible for great earthquakes.

Historical records document several large events nearby, including the magnitude 8.6 Andreanof Islands earthquake of 1957, which generated a trans-Pacific tsunami. Contemporary monitoring by the Alaska Earthquake Center and the USGS confirms that microseismicity remains frequent, with swarms providing insight into the background stress field without indicating immediate escalation to larger ruptures.

Continued observation of swarm patterns contributes to refined seismic hazard assessments for the central Aleutians. The low magnitudes and limited duration observed in VS20221114.1 align with the established behavior of the region and do not alter the long-term probabilistic estimates derived from the instrumental catalog.

References
USGS Earthquake Catalog
Alaska Earthquake Center Regional Seismicity Reports
NOAA National Centers for Environmental Information Tsunami Database