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Location:
18km NE of Olancha, CA
Period:
3 May 2011 14:32:13 - 5 May 2011 00:48:46 (1 day 10 hours 16 minutes)
Volcanoes in 100km radius:
Ubehebe Craters(79km)
Earthquakes:
50
11 swarms found nearby.
2000
S20000426.1(18.2km)
25 Apr
2 days 10 hours
53 earthquakes
S20000517.1(17.3km)
17 May
3 days 15 hours
92 earthquakes
S20000709.1(16.0km)
8 Jul
1 day 22 hours
44 earthquakes
2002
S20020721.1(27.5km)
20 Jul
3 days 21 hours
49 earthquakes
2009
23 May
6 days 9 hours
88 earthquakes
30 Aug
2 days 19 hours
47 earthquakes
30 Sep
19 days 1 hours
636 earthquakes
2020
S20200604.2(29.5km)
3 Jun
5 days 19 hours
148 earthquakes
S20200623.1(11.6km)
22 Jun
25 days 3 hours
1110 earthquakes
2021
S20210412.1(22.4km)
11 Apr
2 days 3 hours
33 earthquakes
S20211018.1(19.3km)
17 Oct
1 day 7 hours
27 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Earthquake Swarm S20110504.2: Seismic Activity Near Olancha, California

An earthquake swarm designated S20110504.2 was recorded 18 km northeast of Olancha, California, in the tectonically active Owens Valley region. The sequence began at 14:32 on 3 May 2011 and concluded at 00:48 on 5 May 2011, spanning 34 hours and 16 minutes. During this period, 50 earthquakes were registered, characteristic of swarm behavior where events cluster closely in time and space without a single dominant mainshock.

The Owens Valley lies within the Eastern California Shear Zone, a zone of distributed right-lateral strike-slip faulting that accommodates part of the Pacific-North America plate motion. This setting features north-northwest trending faults, including segments of the Owens Valley Fault and the Sierra Nevada Frontal Fault system. The area experiences frequent seismicity influenced by both regional tectonics and localized volcanic processes associated with the nearby Coso Volcanic Field, where geothermal activity and shallow crustal heat contribute to episodic swarm sequences.

Event Characteristics and Temporal Distribution

The swarm displayed a range of magnitudes from 0.6 to 4.4, with the majority below magnitude 2.0. Depths varied between 0 km and 12 km, indicating shallow crustal involvement typical of the region. The largest event, magnitude 4.4, occurred on 3 May at 21:41:49 at a depth of 0 km. Subsequent notable events included magnitudes 3.6 and 3.5 on 4 May at 08:10:45 and 08:11:09, respectively, followed by a magnitude 3.0 on 4 May at 11:55:45.

Activity showed clustering, with elevated rates during the evening of 3 May and mid-morning of 4 May. Many events registered at depths of 0–5 km, consistent with fluid migration or stress perturbations in a geothermal-influenced crust. Lower-magnitude events continued through 4 May before tapering off by early 5 May.

Historical Context

Since 1 January 2000, seven swarms have occurred in this locale. Earlier episodes took place in 2000 (three swarms), 2002 (one swarm), and 2009 (three swarms). These recurrent swarms underscore the persistent seismic productivity of the area, driven by ongoing tectonic strain accumulation and hydrothermal influences.

Seismic swarms in this part of California often lack clear foreshock-mainshock-aftershock patterns and instead reflect distributed slip or fluid-driven processes. The 2011 sequence aligns with this pattern, providing data for monitoring crustal dynamics near critical infrastructure and geothermal resources.

References

  • United States Geological Survey Earthquake Catalog
  • California Geological Survey Regional Fault Maps
  • SeismoSight internal swarm classification records