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Location:
13km E of Ridgecrest, CA
Period:
8 May 2020 15:43:39 - 12 May 2020 13:14:26 (3 days 21 hours 30 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
69
33 swarms found nearby.
2013
3 May
1 day 22 hours
37 earthquakes
2019
4 Jul
221 days 12 hours
22493 earthquakes
4 Jul
75 days 9 hours
8149 earthquakes
S20190708.2(24.5km)
7 Jul
4 days 17 hours
70 earthquakes
S20190712.1(24.0km)
11 Jul
16 hours
29 earthquakes
S20190812.1(11.1km)
12 Aug
3 days 6 hours
50 earthquakes
S20190825.1(27.0km)
24 Aug
3 days 7 hours
165 earthquakes
8 Sep
1 day 13 hours
47 earthquakes
S20190910.1(19.6km)
10 Sep
3 days 21 hours
145 earthquakes
1 Oct
4 days 13 hours
127 earthquakes
S20191005.1(28.4km)
5 Oct
3 days 16 hours
147 earthquakes
5 Oct
1 day 18 hours
26 earthquakes
13 Oct
1 day 23 hours
36 earthquakes
15 Oct
2 days 23 hours
108 earthquakes
30 Nov
2 days 16 hours
49 earthquakes
1 Dec
9 days 6 hours
252 earthquakes
13 Dec
22 hours
27 earthquakes
15 Dec
6 days 12 hours
188 earthquakes
22 Dec
10 days 4 hours
196 earthquakes
2020
10 Jan
22 days 10 hours
422 earthquakes
22 Jan
17 hours
24 earthquakes
S20200208.1(11.5km)
7 Feb
1 day 19 hours
44 earthquakes
12 Feb
5 days 22 hours
159 earthquakes
21 Feb
5 days 20 hours
94 earthquakes
S20200322.1(16.5km)
21 Mar
10 days 13 hours
140 earthquakes
14 Apr
7 days 19 hours
130 earthquakes
25 May
1 day 7 hours
31 earthquakes
3 Jun
9 days 16 hours
525 earthquakes
S20200727.1(13.8km)
27 Jul
13 days 20 hours
183 earthquakes
13 Aug
7 days 2 hours
81 earthquakes
21 Sep
5 days 2 hours
99 earthquakes
2021
S20210404.1(28.2km)
3 Apr
11 days 13 hours
124 earthquakes
2022
S20220715.1(16.1km)
14 Jul
4 days 3 hours
55 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm S20200509.1: Activity East of Ridgecrest, California

Seismic swarm S20200509.1 was recorded 13 km east of Ridgecrest, California, beginning at 15:43 on 8 May 2020 and concluding at 13:14 on 12 May 2020. Over 93 hours and 30 minutes, the sequence produced 69 earthquakes. Magnitudes ranged from -0.2 to 2.6, with focal depths between 1 km and 13 km. The largest event reached magnitude 2.6 at a depth of 4 km on 8 May at 20:35:33 UTC. Subsequent notable shocks included a magnitude 2.3 event at 7 km depth on 8 May at 17:10:46 and a magnitude 2.2 shock at 7 km on 9 May at 03:44:03. The majority of events clustered between 4 km and 8 km depth, consistent with shallow crustal faulting in the region.

The swarm occurred within the tectonically active Eastern California Shear Zone, a network of northwest-trending strike-slip faults that accommodate a portion of the Pacific-North America plate motion. Ridgecrest lies near the intersection of the Garlock Fault and the Little Lake Fault Zone, where distributed deformation produces frequent small-magnitude seismicity. The 2019 Ridgecrest earthquake sequence, which included magnitude 6.4 and 7.1 mainshocks, ruptured previously unmapped fault segments in this same area, releasing significant strain and altering local stress conditions. Post-2019 aftershock activity and subsequent swarms reflect ongoing adjustment along these complex fault structures.

Since 1 January 2000, 26 swarms have been documented in the vicinity. Earlier episodes occurred in 2013 (one swarm), 2019 (eighteen swarms), and 2020 (seven swarms including the present sequence). These clusters typically feature low-magnitude events at shallow depths, often without a single dominant mainshock, distinguishing them from classic foreshock-mainshock-aftershock sequences.

Analysis of the 2020 swarm shows a rapid onset followed by a gradual decline in event rate. Early activity on 8 May included several events above magnitude 1.0 within the first six hours. By 10–11 May, most recorded magnitudes remained below 1.0, with only isolated events reaching 1.7–1.8. Depths showed modest variation, with the shallowest events (1–2 km) occurring on 10 and 11 May and deeper events (up to 13 km) scattered throughout. No events exceeded magnitude 3.0, indicating limited energy release compared with the 2019 mainshocks.

The swarm underscores the persistent seismic hazard in the Ridgecrest area. Continued monitoring by regional networks remains essential for tracking stress transfer along the shear zone and assessing potential for larger triggered events.

References

  • United States Geological Survey Earthquake Catalog (USGS)
  • California Geological Survey, Regional Fault and Seismicity Reports
  • SeismoSight internal swarm classification records