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Note:This page contains AI-generated content for informational and entertainment purposes only. It may contain inaccuracies. Raw event data is from USGS and EMSC. All statistics, lists, and derived information are generated by this site. Full disclaimerFound an error?
Location:
65 km WNW of Beluga, Alaska
Period:
2 Dec 2022 20:40:57 - 4 Dec 2022 13:33:50 (1 day 16 hours 52 minutes)
Volcanoes in 100km radius:
Spurr(4km), Hayes(34km), Redoubt(98km)
Earthquakes:
40
15 swarms found nearby.
2021
14 Jun
2 hours
37 earthquakes
2024
19 Feb
1 day 7 hours
27 earthquakes
2 Mar
4 days 4 hours
89 earthquakes
7 Mar
4 days 5 hours
48 earthquakes
25 Apr
3 days 17 hours
68 earthquakes
18 May
3 days 19 hours
80 earthquakes
7 Oct
4 days 19 hours
110 earthquakes
27 Oct
2 days 13 hours
56 earthquakes
1 Nov
3 days 22 hours
85 earthquakes
22 Nov
2 days 17 hours
49 earthquakes
VS20241130.1(19.0km)
30 Nov
53 days 4 hours
1155 earthquakes
2025
VS20250201.1(18.4km)
31 Jan
63 days 9 hours
1115 earthquakes
6 May
25 days 14 hours
387 earthquakes
S20250630.1(13.8km)
29 Jun
7 days 9 hours
78 earthquakes
VS20250717.1(11.8km)
16 Jul
9 days 3 hours
170 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm VS20221203.1: Analysis of Microearthquake Activity Near Beluga, Alaska

A seismic swarm designated VS20221203.1 was recorded 65 km west-northwest of Beluga, Alaska, within the tectonically active Cook Inlet region. The sequence began at 20:40 on 2 December 2022 and concluded at 13:33 on 4 December 2022, spanning 40 hours and 52 minutes. During this interval, 40 earthquakes were detected, with the majority registering negative or near-zero magnitudes indicative of microseismic events.

The events clustered tightly in both time and space. Initial activity on 2 December included a magnitude -0.6 quake at 2 km depth. On 3 December, the swarm intensified with repeated occurrences between 02:06 and 03:08, featuring magnitudes ranging from -0.9 to 1.4 and depths fluctuating between -3 km and 8 km. Notable events included a magnitude 1.0 at 6 km depth at 02:08 and a magnitude 1.4 at 7 km depth at 02:33. Activity tapered on 4 December, with the final event at magnitude -0.4 and -2 km depth. Depths showed variability, including apparent negative values likely reflecting location uncertainties in shallow crustal settings.

The Cook Inlet basin lies above the Alaska-Aleutian subduction zone, where the Pacific Plate converges with the North American Plate at rates exceeding 6 cm per year. This tectonic regime produces frequent crustal and intraslab seismicity, with historical events including the great 1964 Prince William Sound earthquake. The Beluga area experiences moderate background seismicity driven by plate interface locking and upper-plate faulting.

Historical records indicate swarm-type sequences are uncommon in this sector. Since 1 January 2000, only one prior swarm has been documented, occurring in 2021. The VS20221203.1 sequence aligns with patterns of episodic, low-magnitude unrest potentially linked to fluid migration or localized stress adjustments along subsidiary faults.

Such swarms provide valuable data for refining seismic hazard models in south-central Alaska, where energy infrastructure and population centers coexist with active tectonics. Continued monitoring supports improved understanding of precursory signals in subduction-related environments.

References SeismoSight internal classification records for swarm VS20221203.1 USGS Earthquake Hazards Program regional tectonic summaries Alaska Earthquake Center historical seismicity reports