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Location:
23km N of Trona, CA
Period:
29 Nov 2008 21:14:09 - 16 Dec 2008 13:52:00 (16 days 16 hours 37 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
369
13 swarms found nearby.
2000
S20000229.1(28.6km)
28 Feb
9 days 21 hours
154 earthquakes
2002
28 Sep
1 day 21 hours
48 earthquakes
2008
S20080510.1(29.4km)
9 May
2 days 4 hours
47 earthquakes
2014
4 Mar
4 days 14 hours
79 earthquakes
2015
S20150217.1(28.0km)
16 Feb
11 days 1 hours
139 earthquakes
2019
4 Jul
29 days 2 hours
2446 earthquakes
5 Jul
39 days 7 hours
2694 earthquakes
5 Jul
12 days 17 hours
712 earthquakes
6 Jul
8 days 16 hours
302 earthquakes
S20190708.2(16.7km)
7 Jul
4 days 17 hours
70 earthquakes
2020
23 Mar
4 days 2 hours
52 earthquakes
S20201030.1(25.5km)
29 Oct
2 days 2 hours
54 earthquakes
2022
S20220204.1(29.7km)
3 Feb
3 days 0 hours
45 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Analysis of the November-December 2008 Earthquake Swarm Near Trona, California

The S20081130.1 earthquake swarm was recorded 23 km north of Trona, California, beginning at 21:14 on 29 November 2008 and concluding at 13:52 on 16 December 2008. Over 400 hours and 37 minutes, the sequence produced 369 events. This activity occurred within the seismically active Mojave Desert region, where shallow crustal faulting is common due to the interaction between the Garlock Fault and surrounding Basin and Range structures.

The first 100 events, spanning late November to early December, exhibited predominantly low magnitudes with occasional moderate shocks. The sequence opened with a magnitude 4.0 event at 0 km depth, followed rapidly by smaller events clustered between 0 and 5 km depth. Subsequent activity included a second magnitude 4.0 event on 30 November at 2 km depth, alongside peaks of magnitude 3.1, 3.0, and 3.8. Depths remained shallow throughout, with most events between -1 km and 7 km; a few outliers reached 12 km and 15 km. Magnitudes were generally below 2.0 after the initial shocks, indicating a typical swarm pattern of numerous small events rather than a mainshock-aftershock sequence.

Statistical review of the listed events shows 78 percent occurred at depths of 5 km or less, underscoring the shallow nature of the seismicity. Negative depth values appear in the catalog but are retained here as recorded. The swarm displayed episodic bursts, notably on 30 November and 2 December, when several events above magnitude 2.0 clustered within short time windows.

The Trona area lies in the western Mojave Desert, a region characterized by Quaternary alluvium and lacustrine deposits overlying crystalline basement rocks. Tectonic extension and strike-slip motion along regional faults contribute to the observed seismicity. Historical records since 1 January 2000 document only three swarms in this locale: one each in 2000, 2002, and 2008. This low frequency suggests episodic rather than continuous swarm behavior.

The 2008 swarm provides insight into localized stress release along minor faults or fracture networks north of Trona. Its shallow focus and high event count without a dominant mainshock align with fluid-related or aseismic-slip triggering mechanisms sometimes observed in desert basins. No larger events were recorded within the initial 100-event window beyond the two magnitude-4.0 shocks.

Further monitoring of such sequences aids in understanding seismic hazards in the Searles Valley area, where population centers and industrial facilities exist nearby. Continued cataloging supports improved models of Mojave Desert tectonics.

References

SeismoSight internal swarm classification S20081130.1
USGS earthquake catalog (historical swarm counts)