Location:

Period:

7 Dec 2022 12:10:31 - 10 Dec 2022 03:34:21 (2 days 15 hours 23 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

19 swarms found nearby.

2014

S20140801.1(19.4km)

31 Jul

2 days 23 hours

51 earthquakes

S20140805.1(16.3km)

4 Aug

5 days 7 hours

82 earthquakes

S20140819.1(11.3km)

18 Aug

2 days 20 hours

111 earthquakes

S20140824.1(11.7km)

23 Aug

1 day 19 hours

27 earthquakes

S20140829.1(14.0km)

28 Aug

2 days 2 hours

36 earthquakes

S20140915.1(12.1km)

14 Sep

2 days 23 hours

44 earthquakes

S20141001.2(13.6km)

1 Oct

1 day 19 hours

30 earthquakes

S20141031.1(15.4km)

30 Oct

2 days 7 hours

40 earthquakes

S20141104.1(14.1km)

4 Nov

55 days 22 hours

1792 earthquakes

S20141231.1(13.8km)

30 Dec

38 days 0 hours

1571 earthquakes

2015

S20150211.1(12.5km)

11 Feb

26 days 3 hours

529 earthquakes

S20150716.1(14.6km)

15 Jul

4 days 9 hours

258 earthquakes

S20150727.1(10.7km)

26 Jul

9 days 5 hours

152 earthquakes

S20150811.1(13.1km)

10 Aug

10 days 1 hours

158 earthquakes

S20150831.1(12.7km)

30 Aug

2 days 7 hours

43 earthquakes

S20150914.1(14.6km)

13 Sep

32 days 6 hours

545 earthquakes

S20151119.1(11.9km)

18 Nov

6 days 21 hours

137 earthquakes

S20151224.1(11.5km)

24 Dec

18 days 2 hours

467 earthquakes

2025

S20250627.1(7.0km)

26 Jun

2 days 16 hours

38 earthquakes

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Seismic Swarm S20221208.1: Analysis of Activity Near Fort Bidwell, California

An earthquake swarm designated S20221208.1 was recorded in northeastern California, centered approximately 50 km east-northeast of Fort Bidwell. The sequence began at 12:10 on 7 December 2022 and concluded at 03:34 on 10 December 2022, spanning 63 hours and 23 minutes. During this interval, 44 earthquakes were detected, providing a detailed record of clustered seismic activity in a tectonically active region.

The events exhibited magnitudes ranging from 0.8 to 3.1, with the largest shock occurring on 8 December at 16:48. Depths varied between 0 km and 17 km, indicating a predominance of shallow seismicity consistent with near-surface faulting. Early activity on 7 December included multiple events between 1.1 and 1.8 in magnitude at depths of 0–17 km. Subsequent days featured a gradual increase in event frequency, culminating in higher-magnitude shocks on 8 December before tapering on 9 and 10 December. The distribution shows a concentration of events at very shallow depths (0–5 km), interspersed with deeper occurrences that may reflect fluid migration or stress transfer along local structures.

The swarm occurred within the Modoc Plateau, a volcanic province influenced by Basin and Range extension. This geological setting features normal faults and volcanic rocks formed during Miocene to Quaternary volcanism. Regional tectonics involve east-west crustal stretching, producing north-south trending faults capable of generating both tectonic and volcanic-related seismicity. Fort Bidwell lies near the transition between the Sierra Nevada and the Basin and Range, where historical deformation has produced scattered earthquake clusters.

Seismic swarms have been documented in this area since at least 2000, with a total of 18 recorded sequences. Notable prior episodes occurred in 2014 (10 events) and 2015 (8 events), suggesting episodic unrest possibly linked to hydrothermal or magmatic processes at depth. Such patterns align with the broader tectonic framework of northeastern California, where low-magnitude swarms frequently occur without producing significant surface rupture.

Monitoring of these sequences contributes to understanding regional strain accumulation and potential volcanic hazards in the Modoc Plateau. Continued observation remains essential given the area's proximity to populated zones and geothermal resources.

References

USGS Earthquake Catalog (earthquake.usgs.gov)
California Geological Survey regional reports
SeismoSight internal swarm classification data