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Location:
17km S of Trona, CA
Period:
12 Aug 2019 00:05:12 - 15 Aug 2019 06:08:18 (3 days 6 hours 3 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
50
28 swarms found nearby.
2013
S20130504.1(11.7km)
3 May
1 day 22 hours
37 earthquakes
2019
S20190704.1(17.4km)
4 Jul
221 days 12 hours
22493 earthquakes
4 Jul
75 days 9 hours
8149 earthquakes
S20190909.2(14.7km)
8 Sep
1 day 13 hours
47 earthquakes
S20190910.1(29.7km)
10 Sep
3 days 21 hours
145 earthquakes
S20191002.1(16.0km)
1 Oct
4 days 13 hours
127 earthquakes
5 Oct
1 day 18 hours
26 earthquakes
13 Oct
1 day 23 hours
36 earthquakes
S20191016.2(10.4km)
15 Oct
2 days 23 hours
108 earthquakes
30 Nov
2 days 16 hours
49 earthquakes
S20191202.1(10.1km)
1 Dec
9 days 6 hours
252 earthquakes
S20191214.1(14.3km)
13 Dec
22 hours
27 earthquakes
S20191216.1(12.4km)
15 Dec
6 days 12 hours
188 earthquakes
S20191223.1(11.1km)
22 Dec
10 days 4 hours
196 earthquakes
2020
S20200111.1(13.1km)
10 Jan
22 days 10 hours
422 earthquakes
S20200122.3(11.4km)
22 Jan
17 hours
24 earthquakes
S20200208.1(21.2km)
7 Feb
1 day 19 hours
44 earthquakes
S20200213.1(18.0km)
12 Feb
5 days 22 hours
159 earthquakes
S20200222.1(11.7km)
21 Feb
5 days 20 hours
94 earthquakes
S20200322.1(26.6km)
21 Mar
10 days 13 hours
140 earthquakes
14 Apr
7 days 19 hours
130 earthquakes
S20200509.1(11.1km)
8 May
3 days 21 hours
69 earthquakes
S20200526.1(14.8km)
25 May
1 day 7 hours
31 earthquakes
S20200604.1(15.8km)
3 Jun
9 days 16 hours
525 earthquakes
S20200727.1(24.2km)
27 Jul
13 days 20 hours
183 earthquakes
13 Aug
7 days 2 hours
81 earthquakes
S20200921.1(15.3km)
21 Sep
5 days 2 hours
99 earthquakes
2022
S20220715.1(25.4km)
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 S20190812.1 Near Trona, California: Geological Context and Event Analysis

The seismic swarm designated S20190812.1 occurred approximately 17 km south of Trona in San Bernardino County, California. This sequence began at 00:05 UTC on 12 August 2019 and concluded at 06:08 UTC on 15 August 2019, spanning 78 hours and 3 minutes. During this period, 50 earthquakes were recorded, providing a detailed snapshot of localized crustal activity in the region.

The Trona area lies within the Searles Valley, part of the Mojave Desert's tectonically active landscape. This zone forms a transition between the Eastern California Shear Zone and the Basin and Range Province, where northwest-trending strike-slip faults accommodate dextral shear between the Pacific and North American plates. The Garlock Fault, located nearby to the north, and segments of the San Andreas system influence regional strain accumulation. Historical deformation has produced both strike-slip and normal faulting, with Quaternary sediments overlying crystalline basement rocks that facilitate shallow seismicity.

Seismic swarms in this setting often reflect fluid migration or aseismic slip along fault networks rather than mainshock-aftershock sequences. The 2019 activity aligns with patterns observed in prior events, underscoring the area's persistent low-to-moderate seismicity. Since 2000, three swarms have been documented in the vicinity, with one occurring in 2013 and two in 2019.

Analysis of the S20190812.1 sequence reveals predominantly small-magnitude events. The largest recorded shocks reached 2.4 on 12 August at 19:36:14 UTC (depth 10 km) and 2.2 on both 14 August at 18:32:30 UTC (depth 7 km) and 15 August at 06:08:18 UTC (depth 4 km). Most events clustered between magnitudes 0.6 and 2.1, with depths ranging from 1 km to 14 km. Shallower events (under 5 km) were frequent during the initial 24 hours, while deeper activity (8–14 km) appeared sporadically on 13–15 August. Temporal distribution showed peak rates on 12 August, with 32 events, followed by a decline to 13 events on 13–14 August and 5 on 15 August.

These characteristics indicate a compact source volume consistent with swarm behavior in the Eastern California Shear Zone. No damage or felt reports were associated with the sequence, typical for events below magnitude 3.0 in this sparsely populated desert terrain.

The swarm's timing followed the major July 2019 Ridgecrest sequence by roughly one month, suggesting possible stress triggering across nearby fault strands, though direct causal links remain under study by regional networks.

References

  • United States Geological Survey Earthquake Catalog (earthquake.usgs.gov)
  • California Geological Survey, Regional Fault and Seismic Hazard Reports
  • SeismoSight internal swarm classification database