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Location:
105 km W of Adak, Alaska
Period:
4 Mar 2023 00:18:18 - 30 Apr 2023 17:22:26 (57 days 17 hours 4 minutes)
Volcanoes in 100km radius:
Tanaga(5km), Takawangha(5km), Bobrof(44km), Gareloi(49km), Kanaga(63km), Moffett(92km)
Earthquakes:
4231
15 swarms found nearby.
2006
PS20060708.1(109.5km)
8 Jul
9 hours
10 earthquakes
PS20060826.1(113.2km)
26 Aug
47 minutes
6 earthquakes
2007
PS20071219.1(113.6km)
19 Dec
19 hours
12 earthquakes
2008
S20080502.3(16.0km)
2 May
10 days 5 hours
184 earthquakes
2017
S20170124.1(11.8km)
23 Jan
2 days 23 hours
126 earthquakes
2018
S20180927.1(26.3km)
27 Sep
1 day 9 hours
40 earthquakes
2020
S20200122.2(19.1km)
22 Jan
10 days 13 hours
627 earthquakes
2021
S20210224.2(17.0km)
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
10 Feb
2 days 6 hours
71 earthquakes
17 Feb
6 days 13 hours
309 earthquakes
28 Feb
1 day 15 hours
114 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 VS20230304.1 Near Adak, Alaska: Geological Context and Event Analysis

A significant seismic swarm, designated VS20230304.1, occurred west of Adak in the Aleutian Islands of Alaska. The sequence began at 00:18 on 4 March 2023 and concluded at 17:22 on 30 April 2023. Over 1385 hours and 4 minutes, 4231 earthquakes were recorded at a location 105 km west of Adak.

The Aleutian Islands form part of an active volcanic arc resulting from the subduction of the Pacific Plate beneath the North American Plate. This tectonic setting produces frequent seismicity, with earthquakes commonly occurring at shallow to intermediate depths along the megathrust interface and within the overriding plate. The region experiences one of the highest rates of seismic activity in the United States due to its position on the Pacific Ring of Fire.

Analysis of the first 100 events reveals predominantly low-magnitude earthquakes, with the largest reaching 2.5. Depths clustered between 3 km and 19 km, indicating activity within the upper crust. Early events on 4 March showed magnitudes between 0.5 and 2.5 at depths of 10–19 km. Subsequent activity through 7 March included several events near 2.0–2.3 magnitude at progressively shallower depths, some as shallow as 1–5 km. The pattern suggests a concentrated release of stress in a localized fault zone without immediate progression to larger mainshock-aftershock sequences.

Historical records indicate 14 seismic swarms in the area since 2000. These occurred in 2006 (two swarms), 2007, 2008, 2017, 2018, 2020, 2021, and multiple episodes in 2022 and 2023. Such recurrent swarms are characteristic of the Aleutian subduction environment, where fluid migration and aseismic slip can trigger episodic earthquake clusters.

The swarm VS20230304.1 fits within this established pattern of moderate, shallow seismicity west of Adak. Continued monitoring remains essential given the tectonic regime's potential for larger events.

References

USGS Earthquake Hazards Program – Aleutian Arc Tectonic Summary
Alaska Earthquake Center – Regional Seismicity Reports
SeismoSight internal swarm classification data (VS20230304.1)