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Location:
15 km WSW of Searles Valley, CA
Period:
14 Apr 2020 21:27:40 - 22 Apr 2020 16:50:51 (7 days 19 hours 23 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
130
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(27.0km)
7 Jul
4 days 17 hours
70 earthquakes
S20190712.1(24.6km)
11 Jul
16 hours
29 earthquakes
12 Aug
3 days 6 hours
50 earthquakes
S20190825.1(27.8km)
24 Aug
3 days 7 hours
165 earthquakes
8 Sep
1 day 13 hours
47 earthquakes
S20190910.1(20.1km)
10 Sep
3 days 21 hours
145 earthquakes
1 Oct
4 days 13 hours
127 earthquakes
S20191005.1(29.2km)
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(11.7km)
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(17.0km)
21 Mar
10 days 13 hours
140 earthquakes
8 May
3 days 21 hours
69 earthquakes
25 May
1 day 7 hours
31 earthquakes
3 Jun
9 days 16 hours
525 earthquakes
S20200727.1(14.6km)
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(28.9km)
3 Apr
11 days 13 hours
124 earthquakes
2022
S20220715.1(16.0km)
14 Jul
4 days 3 hours
55 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Analysis of Seismic Swarm S20200415.1 near Searles Valley, California

Seismic swarm S20200415.1 was recorded in the Searles Valley region of California, beginning at 21:27 on 14 April 2020 and concluding at 16:50 on 22 April 2020. The sequence lasted 187 hours and 23 minutes, during which 130 earthquakes were detected approximately 15 km west-southwest of Searles Valley. This event aligns with patterns of clustered seismicity observed in the area since 2000, when a total of 25 swarms have occurred, including one in 2013, 18 in 2019, and six in 2020.

Analysis of the first 100 events reveals predominantly low-magnitude activity, with values ranging from -0.1 to 2.5. The initial event registered magnitude 1.3 at a depth of 3 km. Subsequent shocks remained shallow, typically between 1 km and 13 km depth, and most magnitudes stayed below 2.0. Notable peaks included a magnitude 2.5 event on 15 April at 7 km depth, a magnitude 2.2 on 16 April at 8 km, and a magnitude 2.4 on 17 April at 8 km. Depths showed no consistent deepening trend, suggesting distributed brittle failure within the upper crust rather than a single fault plane rupture.

The timing of events indicates episodic clustering, with bursts of activity separated by quieter intervals. For instance, multiple events occurred within minutes on 15 April and again on 16 April. Negative magnitudes appeared briefly on 16 April, reflecting the sensitivity of the monitoring network to very small events. Overall, the swarm lacked a dominant mainshock, consistent with fluid-driven or stress-transfer mechanisms common in this tectonic setting.

The Searles Valley lies within the Mojave Desert portion of the eastern California shear zone, a region characterized by northwest-trending strike-slip faults and distributed deformation between the San Andreas and Walker Lane systems. The nearby Garlock Fault, a major left-lateral structure, influences local stress fields and has hosted historical seismicity. Searles Lake, a Pleistocene-era playa, overlies basin-fill sediments that overlie crystalline basement rocks, conditions that can facilitate shallow seismicity through pore-pressure changes.

Seismic swarms in this area have increased in frequency following the 2019 Ridgecrest earthquake sequence, which altered regional stress and triggered afterslip along adjacent faults. The 2020 activity, including S20200415.1, fits within this post-2019 elevated rate. Depths consistently under 13 km align with the brittle-ductile transition typical of the Mojave crust, where temperatures allow frictional sliding at shallow levels.

Continued monitoring of such swarms provides insight into fault interactions and potential precursors to larger events along the Garlock system. The low magnitudes and shallow depths observed here indicate minimal surface rupture risk but underscore the value of dense seismic networks for tracking evolving hazard in tectonically active basins.

References

USGS Earthquake Catalog California Geological Survey fault database SeismoSight internal swarm classification records