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Location:
7km SE of Coso Junction, CA
Period:
11 Apr 2021 07:58:23 - 13 Apr 2021 11:24:00 (2 days 3 hours 25 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
33
86 swarms found nearby.
2000
S20000229.1(28.2km)
28 Feb
9 days 21 hours
154 earthquakes
S20000329.1(17.8km)
28 Mar
9 days 13 hours
115 earthquakes
S20000426.1(20.5km)
25 Apr
2 days 10 hours
53 earthquakes
S20000517.1(21.7km)
17 May
3 days 15 hours
92 earthquakes
S20000709.1(21.2km)
8 Jul
1 day 22 hours
44 earthquakes
S20000911.1(16.5km)
10 Sep
9 days 14 hours
140 earthquakes
S20000921.1(15.7km)
20 Sep
15 days 13 hours
274 earthquakes
2001
S20010408.1(17.6km)
7 Apr
1 day 16 hours
29 earthquakes
S20010423.1(15.7km)
23 Apr
8 days 21 hours
256 earthquakes
S20010610.1(18.3km)
9 Jun
4 days 3 hours
51 earthquakes
S20010714.1(15.6km)
14 Jul
67 days 13 hours
5060 earthquakes
2002
20 Jul
3 days 21 hours
49 earthquakes
S20020907.1(15.7km)
6 Sep
2 days 1 hours
31 earthquakes
2004
S20040224.2(19.0km)
24 Feb
1 day 20 hours
36 earthquakes
S20040328.1(24.6km)
28 Mar
4 days 0 hours
71 earthquakes
S20040402.1(24.1km)
2 Apr
1 day 9 hours
28 earthquakes
S20040629.1(19.2km)
28 Jun
3 days 22 hours
108 earthquakes
S20040712.1(15.6km)
11 Jul
17 days 11 hours
158 earthquakes
S20040807.1(16.2km)
6 Aug
8 days 18 hours
101 earthquakes
S20040915.1(20.5km)
14 Sep
8 days 20 hours
86 earthquakes
S20040925.1(13.3km)
24 Sep
4 days 9 hours
57 earthquakes
S20041202.1(18.0km)
1 Dec
2 days 18 hours
36 earthquakes
2005
S20050806.1(16.9km)
6 Aug
7 days 5 hours
120 earthquakes
S20050926.1(20.4km)
25 Sep
1 day 9 hours
41 earthquakes
2006
S20060104.1(23.2km)
3 Jan
2 days 16 hours
37 earthquakes
S20060324.1(21.3km)
23 Mar
4 days 11 hours
67 earthquakes
S20060713.1(15.9km)
12 Jul
6 days 5 hours
67 earthquakes
12 Aug
8 days 13 hours
97 earthquakes
S20060824.1(21.9km)
23 Aug
8 days 12 hours
89 earthquakes
S20061127.1(24.5km)
27 Nov
7 days 11 hours
109 earthquakes
2009
S20090524.1(25.0km)
23 May
6 days 9 hours
88 earthquakes
S20090830.1(23.7km)
30 Aug
2 days 19 hours
47 earthquakes
S20091001.2(22.0km)
30 Sep
19 days 1 hours
636 earthquakes
S20091231.1(25.8km)
31 Dec
1 day 18 hours
54 earthquakes
2010
S20100114.1(17.9km)
13 Jan
11 days 8 hours
443 earthquakes
S20100302.1(12.8km)
1 Mar
5 days 11 hours
44 earthquakes
S20100424.1(18.2km)
23 Apr
2 days 15 hours
41 earthquakes
S20101019.1(29.1km)
18 Oct
2 days 0 hours
40 earthquakes
S20101024.1(26.3km)
23 Oct
7 days 5 hours
92 earthquakes
S20101125.1(20.7km)
25 Nov
1 day 13 hours
36 earthquakes
2011
S20110504.2(22.4km)
3 May
1 day 10 hours
50 earthquakes
2012
S20120106.1(13.4km)
6 Jan
2 days 18 hours
48 earthquakes
S20121024.1(23.0km)
23 Oct
6 days 5 hours
80 earthquakes
S20121127.1(11.4km)
26 Nov
24 days 0 hours
802 earthquakes
2013
S20130321.1(19.4km)
20 Mar
4 days 15 hours
80 earthquakes
S20130406.1(20.1km)
5 Apr
3 days 20 hours
59 earthquakes
S20130611.1(16.1km)
10 Jun
3 days 18 hours
43 earthquakes
S20130804.1(17.7km)
4 Aug
1 day 20 hours
50 earthquakes
S20130812.1(29.1km)
11 Aug
2 days 13 hours
64 earthquakes
S20131223.1(18.8km)
23 Dec
5 days 10 hours
116 earthquakes
2014
S20140321.1(21.7km)
20 Mar
1 day 19 hours
35 earthquakes
S20140701.1(12.9km)
30 Jun
8 days 23 hours
167 earthquakes
2015
S20150217.1(28.8km)
16 Feb
11 days 1 hours
139 earthquakes
8 Jun
1 day 13 hours
31 earthquakes
2016
S20160331.1(17.7km)
30 Mar
1 day 14 hours
27 earthquakes
S20160821.1(20.6km)
20 Aug
2 days 0 hours
37 earthquakes
S20161206.1(20.5km)
5 Dec
6 days 9 hours
75 earthquakes
2017
S20170521.1(20.4km)
20 May
1 day 16 hours
35 earthquakes
S20170608.1(20.1km)
8 Jun
3 days 3 hours
52 earthquakes
2018
S20181130.1(24.8km)
29 Nov
2 days 17 hours
51 earthquakes
2019
S20190318.1(18.7km)
17 Mar
4 days 6 hours
102 earthquakes
S20190511.1(19.9km)
10 May
5 days 12 hours
90 earthquakes
S20190525.1(27.9km)
24 May
1 day 12 hours
43 earthquakes
S20190528.1(27.8km)
28 May
2 days 3 hours
61 earthquakes
S20190721.1(11.0km)
20 Jul
9 days 5 hours
474 earthquakes
S20190803.1(29.4km)
2 Aug
2 days 8 hours
77 earthquakes
S20190804.1(29.5km)
4 Aug
41 days 17 hours
1154 earthquakes
S20190809.1(25.9km)
8 Aug
1 day 18 hours
60 earthquakes
S20190906.1(24.8km)
5 Sep
1 day 4 hours
27 earthquakes
S20190915.1(28.9km)
14 Sep
25 days 14 hours
387 earthquakes
S20191116.2(15.7km)
16 Nov
3 days 4 hours
90 earthquakes
S20191201.1(11.4km)
30 Nov
27 days 2 hours
353 earthquakes
2020
S20200107.2(15.7km)
7 Jan
11 days 11 hours
163 earthquakes
S20200228.1(25.0km)
27 Feb
7 days 2 hours
113 earthquakes
S20200305.2(25.1km)
5 Mar
1 day 5 hours
42 earthquakes
6 Mar
10 days 22 hours
145 earthquakes
S20200324.1(10.3km)
23 Mar
6 days 13 hours
82 earthquakes
S20200509.2(12.7km)
8 May
3 days 23 hours
49 earthquakes
3 Jun
5 days 19 hours
148 earthquakes
2021
S20210117.1(18.3km)
17 Jan
9 hours
25 earthquakes
12 Feb
1 day 17 hours
29 earthquakes
S20210616.1(15.4km)
15 Jun
4 days 20 hours
83 earthquakes
17 Oct
1 day 7 hours
27 earthquakes
S20211029.2(13.0km)
29 Oct
3 days 9 hours
48 earthquakes
18 Dec
13 days 0 hours
143 earthquakes
2024
15 Apr
2 days 15 hours
51 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm S20210412.1 Near Coso Junction, California

A seismic swarm designated S20210412.1 was recorded 7 km southeast of Coso Junction, California. The sequence began at 07:58 on 11 April 2021 and concluded at 11:24 on 13 April 2021, spanning 51 hours and 25 minutes. During this interval, 33 earthquakes were detected, with magnitudes ranging from 0.0 to 2.4 and focal depths primarily between 1 and 5 km.

The Coso region lies within the eastern California shear zone, a tectonically active area characterized by right-lateral strike-slip faulting and extensional Basin and Range structures. The Coso Volcanic Field, situated nearby, features Quaternary rhyolitic domes, basaltic flows, and an active geothermal system that has produced electricity since the 1980s. This volcanic field is underlain by a shallow crustal magma body that influences local seismicity through hydrothermal fluid circulation and thermal stressing of faults.

Earthquake swarms are common in the Coso area due to the interplay between tectonic strain and geothermal processes. Historical records indicate 81 swarms have occurred since 1 January 2000. Annual counts include 7 swarms in 2000, 4 in 2001, 2 in 2002, 9 in 2004, 2 in 2005, 6 in 2006, 4 in 2009, 6 in 2010, 1 in 2011, 3 in 2012, 6 in 2013, 2 in 2014, 2 in 2015, 3 in 2016, 2 in 2017, 1 in 2018, 12 in 2019, 7 in 2020, and 2 in 2021. These events typically involve low-magnitude earthquakes clustered in time and space without a distinct mainshock-aftershock pattern.

Within swarm S20210412.1, the largest event reached magnitude 2.4 at a depth of 2 km on 11 April at 10:21. Most events occurred at depths of 1–3 km, consistent with the shallow brittle-ductile transition in this geothermal setting. Activity was highest on 11 April, with 20 events recorded, followed by 11 on 12 April and 2 on 13 April.

Such swarms contribute to ongoing monitoring of volcanic and seismic hazards in the region. The Coso Volcanic Field remains a focus for geothermal development and geophysical research because of its elevated heat flow and frequent microseismicity.

References

  • United States Geological Survey Earthquake Catalog
  • California Geological Survey Regional Fault Maps
  • Coso Geothermal Field Operational Reports (Bureau of Land Management)