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Location:
10km ENE of Coso Junction, CA
Period:
5 Jul 2019 18:15:20 - 18 Jul 2019 12:04:50 (12 days 17 hours 49 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
712
18 swarms found nearby.
2002
28 Sep
1 day 21 hours
48 earthquakes
2008
S20080510.1(28.6km)
9 May
2 days 4 hours
47 earthquakes
29 Nov
16 days 16 hours
369 earthquakes
2014
4 Mar
4 days 14 hours
79 earthquakes
2019
4 Jul
29 days 2 hours
2446 earthquakes
5 Jul
39 days 7 hours
2694 earthquakes
6 Jul
8 days 16 hours
302 earthquakes
S20190708.2(12.3km)
7 Jul
4 days 17 hours
70 earthquakes
S20190712.1(29.6km)
11 Jul
16 hours
29 earthquakes
S20190825.1(29.2km)
24 Aug
3 days 7 hours
165 earthquakes
S20190910.1(29.7km)
10 Sep
3 days 21 hours
145 earthquakes
S20191005.1(29.9km)
5 Oct
3 days 16 hours
147 earthquakes
2020
S20200101.1(29.2km)
1 Jan
7 days 0 hours
130 earthquakes
S20200322.1(29.4km)
21 Mar
10 days 13 hours
140 earthquakes
23 Mar
4 days 2 hours
52 earthquakes
S20200727.1(28.5km)
27 Jul
13 days 20 hours
183 earthquakes
S20200921.1(29.9km)
21 Sep
5 days 2 hours
99 earthquakes
2021
S20210404.1(29.6km)
3 Apr
11 days 13 hours
124 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm S20190706.4: Analysis of Activity Near Coso Junction, California

Seismic swarm S20190706.4 occurred approximately 10 km east-northeast of Coso Junction in California. The sequence began at 18:15 on 5 July 2019 and concluded at 12:04 on 18 July 2019, spanning 305 hours and 49 minutes. During this period, 712 earthquakes were recorded.

Analysis of the first 100 events reveals predominantly low-magnitude seismicity. Magnitudes ranged from 0.2 to 3.5, with the largest event reaching 3.5 on 6 July at 15:45:46. Depths were shallow, mostly between 1 km and 8 km, consistent with activity in the upper crust. Several events clustered near 2–5 km depth, while a few registered at or slightly below surface level. The initial event on 5 July registered magnitude 0.9 at 7 km depth, followed by a rapid increase in activity on 6 July, including multiple events above magnitude 2.0 within the first hours.

The Coso region lies within the Coso Volcanic Field, a late Cenozoic volcanic center in the western Basin and Range province of eastern California. This field features rhyolitic domes, basaltic flows, and an active geothermal system driven by shallow crustal heat sources. The area experiences frequent earthquake swarms linked to fluid migration and tectonic extension along normal faults. Historical records indicate six swarms since 2000, occurring in 2002, 2008 (two episodes), 2014, and 2019 (two episodes). These sequences typically involve hundreds of events over days to weeks, with low maximum magnitudes and shallow focal depths.

Geological monitoring in the Coso Volcanic Field benefits from dense seismic networks operated by regional and federal agencies. The observed swarm characteristics align with patterns seen in prior episodes, where seismicity is often attributed to hydrothermal processes rather than magmatic intrusion. Depths recorded in the initial 100 events match the typical 1–10 km range for shallow crustal events in this extensional setting.

References
United States Geological Survey Earthquake Catalog
California Geological Survey Regional Fault Maps
Coso Volcanic Field geothermal studies, Naval Air Weapons Station China Lake reports