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Location:
Andreanof Islands, Aleutian Islands, Alaska
Period:
10 Feb 2023 19:16:51 - 13 Feb 2023 01:49:12 (2 days 6 hours 32 minutes)
Volcanoes in 100km radius:
Takawangha(1km), Tanaga(10km), Bobrof(39km), Gareloi(55km), Kanaga(57km), Moffett(86km)
Earthquakes:
71
12 swarms found nearby.
2006
PS20060708.1(113.3km)
8 Jul
9 hours
10 earthquakes
2008
S20080502.3(10.5km)
2 May
10 days 5 hours
184 earthquakes
2017
23 Jan
2 days 23 hours
126 earthquakes
2020
S20200122.2(13.6km)
22 Jan
10 days 13 hours
627 earthquakes
2021
S20210224.2(11.4km)
23 Feb
1 day 16 hours
34 earthquakes
2022
13 Nov
1 day 7 hours
42 earthquakes
17 Nov
7 days 23 hours
341 earthquakes
12 Dec
10 days 11 hours
186 earthquakes
2023
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 in the Andreanof Islands, Aleutian Arc: February 2023 Analysis

The Andreanof Islands form part of the central Aleutian Islands chain in Alaska, situated along a tectonically active subduction zone where the Pacific Plate converges with and descends beneath the North American Plate. This setting generates frequent seismic events, including earthquake swarms, due to stresses along the megathrust interface and associated crustal faults. The region lies within the Aleutian volcanic arc, characterized by stratovolcanoes and a history of both volcanic and tectonic activity.

Earthquake swarms in this area typically involve clusters of events without a dominant mainshock, often linked to fluid migration or aseismic slip. The swarm designated VS20230211.1 began at 19:16 on 10 February 2023 and concluded at 01:49 on 13 February 2023, lasting 54 hours and 32 minutes. During this period, 71 earthquakes were recorded, with magnitudes ranging from -0.1 to 2.7 and depths predominantly between 2 and 11 km. Most events clustered at shallow depths of 3–5 km, though a few reached 10–11 km. The sequence featured numerous low-magnitude tremors (below 1.0) interspersed with occasional events above magnitude 1.0, including peaks at 2.7, 2.6, and 2.1 on 12 February.

This activity aligns with the broader seismic character of the Andreanof Islands, where the subduction zone accommodates convergence rates of approximately 6–7 cm per year. Historical records document eight swarms in the region since 2000, occurring in 2006, 2008, 2017, 2020, 2021, and three instances in 2022. Such recurrent swarms reflect ongoing strain accumulation and release along the plate boundary.

The Aleutian subduction zone has produced major earthquakes throughout recorded history, notably the 1957 Andreanof Islands event of magnitude 8.6, which generated a significant tsunami. Modern monitoring by networks such as the Alaska Earthquake Center confirms persistent microseismicity, underscoring the area's elevated hazard potential. The February 2023 swarm remained at low magnitudes and produced no reported damage or felt shaking beyond instrumental detection.

References
USGS Earthquake Hazards Program – Aleutian Islands tectonics overview
Alaska Earthquake Center – Regional seismic monitoring data
SeismoSight internal swarm classification records (VS20230211.1)