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Location:
7km ENE of Westmorland, CA
Period:
15 Dec 2010 14:09:07 - 16 Dec 2010 18:59:42 (1 day 4 hours 50 minutes)
Volcanoes in 100km radius:
Salton Buttes(21km), Prieto, Cerro(70km)
Earthquakes:
101
105 swarms found nearby.
2000
VS20000512.1(20.1km)
11 May
2 days 10 hours
52 earthquakes
S20000614.1(16.3km)
14 Jun
2 days 16 hours
145 earthquakes
2002
S20020225.1(18.6km)
24 Feb
1 day 2 hours
31 earthquakes
2003
S20030301.1(10.3km)
1 Mar
23 hours
52 earthquakes
VS20030413.1(19.7km)
13 Apr
1 day 18 hours
32 earthquakes
23 May
1 day 22 hours
161 earthquakes
VS20030920.1(20.0km)
20 Sep
1 day 8 hours
31 earthquakes
2004
VS20040316.1(20.7km)
15 Mar
2 days 20 hours
64 earthquakes
2005
VS20050829.1(19.7km)
29 Aug
10 hours
24 earthquakes
VS20050831.1(21.1km)
31 Aug
11 days 21 hours
953 earthquakes
S20050920.1(22.3km)
19 Sep
2 days 11 hours
50 earthquakes
2008
VS20080316.1(22.3km)
15 Mar
5 days 22 hours
111 earthquakes
S20080527.1(22.0km)
27 May
9 hours
47 earthquakes
2 Jun
2 days 13 hours
145 earthquakes
VS20080929.1(19.8km)
29 Sep
1 day 4 hours
37 earthquakes
2009
VS20090417.1(19.4km)
17 Apr
1 day 13 hours
29 earthquakes
S20090614.1(18.8km)
13 Jun
1 day 5 hours
53 earthquakes
VS20090801.1(24.4km)
1 Aug
3 days 10 hours
106 earthquakes
24 Sep
19 hours
28 earthquakes
S20091003.1(19.2km)
2 Oct
2 days 23 hours
43 earthquakes
S20091101.1(26.5km)
1 Nov
12 hours
26 earthquakes
VS20091107.1(19.9km)
7 Nov
5 hours
36 earthquakes
VS20091117.1(19.2km)
17 Nov
1 day 19 hours
142 earthquakes
VS20091124.1(20.7km)
23 Nov
4 days 3 hours
69 earthquakes
2010
VS20100111.1(20.1km)
10 Jan
10 days 2 hours
233 earthquakes
VS20100123.1(18.6km)
22 Jan
2 days 3 hours
46 earthquakes
VS20100222.1(21.3km)
21 Feb
1 day 20 hours
28 earthquakes
S20100405.3(19.7km)
4 Apr
6 days 21 hours
132 earthquakes
PS20100405.1(91.6km)
4 Apr
1 hours
5 earthquakes
VS20100423.1(19.6km)
22 Apr
1 day 4 hours
38 earthquakes
VS20100806.1(20.1km)
5 Aug
1 day 0 hours
26 earthquakes
VS20101112.1(24.4km)
11 Nov
1 day 10 hours
28 earthquakes
13 Dec
12 hours
49 earthquakes
VS20101228.1(19.3km)
27 Dec
11 hours
66 earthquakes
S20110101.1(19.2km)
31 Dec
1 day 14 hours
33 earthquakes
2011
VS20110108.1(22.0km)
7 Jan
2 days 20 hours
94 earthquakes
VS20110328.1(22.3km)
27 Mar
1 day 18 hours
42 earthquakes
VS20110402.1(20.2km)
2 Apr
1 day 12 hours
34 earthquakes
S20110701.1(18.7km)
1 Jul
1 day 2 hours
36 earthquakes
S20110715.2(19.0km)
15 Jul
2 days 3 hours
36 earthquakes
2012
S20120209.1(21.9km)
8 Feb
2 days 0 hours
29 earthquakes
VS20120219.1(23.5km)
19 Feb
1 day 18 hours
86 earthquakes
VS20120226.1(19.3km)
26 Feb
2 days 1 hours
88 earthquakes
S20120229.1(21.8km)
29 Feb
14 hours
34 earthquakes
VS20120304.1(20.5km)
3 Mar
3 days 11 hours
72 earthquakes
VS20120323.1(20.5km)
22 Mar
2 days 22 hours
73 earthquakes
S20120521.1(19.9km)
20 May
2 days 1 hours
33 earthquakes
VS20120608.1(20.1km)
8 Jun
19 hours
95 earthquakes
26 Aug
11 days 23 hours
972 earthquakes
S20120925.1(18.5km)
24 Sep
1 day 17 hours
51 earthquakes
2013
S20130219.1(17.7km)
18 Feb
4 days 14 hours
57 earthquakes
VS20130404.1(18.3km)
3 Apr
2 days 12 hours
59 earthquakes
S20130429.1(18.8km)
28 Apr
2 days 2 hours
41 earthquakes
VS20130516.1(22.0km)
16 May
5 days 21 hours
135 earthquakes
VS20130603.1(18.6km)
3 Jun
3 days 15 hours
134 earthquakes
S20130820.1(15.3km)
19 Aug
3 days 21 hours
47 earthquakes
S20130828.1(18.7km)
27 Aug
1 day 17 hours
37 earthquakes
VS20131009.1(18.8km)
8 Oct
1 day 23 hours
83 earthquakes
S20131014.1(19.0km)
13 Oct
2 days 10 hours
83 earthquakes
S20131016.1(19.6km)
16 Oct
1 day 21 hours
50 earthquakes
VS20131101.1(20.3km)
31 Oct
16 hours
31 earthquakes
S20131127.1(17.6km)
27 Nov
1 day 7 hours
52 earthquakes
VS20131222.1(18.8km)
21 Dec
1 day 8 hours
65 earthquakes
2014
VS20140328.1(23.0km)
28 Mar
1 day 16 hours
34 earthquakes
2015
VS20150521.1(17.5km)
21 May
1 day 13 hours
38 earthquakes
2016
VS20160729.1(21.9km)
29 Jul
1 day 9 hours
30 earthquakes
S20160926.1(29.8km)
26 Sep
6 days 7 hours
322 earthquakes
VS20161031.1(19.5km)
31 Oct
23 hours
39 earthquakes
31 Dec
3 days 4 hours
317 earthquakes
2017
S20170313.1(20.5km)
13 Mar
12 hours
24 earthquakes
S20170807.1(23.3km)
7 Aug
16 hours
40 earthquakes
2018
S20180618.1(14.9km)
17 Jun
1 day 9 hours
26 earthquakes
2019
S20190115.1(15.8km)
15 Jan
4 hours
24 earthquakes
S20190118.1(16.6km)
17 Jan
4 days 13 hours
71 earthquakes
S20191112.1(24.5km)
12 Nov
1 day 4 hours
84 earthquakes
2020
VS20200506.1(18.8km)
5 May
1 day 14 hours
56 earthquakes
S20200810.1(22.6km)
9 Aug
4 days 12 hours
319 earthquakes
S20200930.1(12.7km)
30 Sep
9 days 1 hours
1724 earthquakes
VS20201022.1(14.9km)
22 Oct
2 days 5 hours
53 earthquakes
VS20201113.1(11.0km)
13 Nov
23 hours
38 earthquakes
VS20201127.1(19.1km)
26 Nov
1 day 10 hours
27 earthquakes
2021
VS20210104.1(19.9km)
4 Jan
21 hours
43 earthquakes
VS20210110.1(19.4km)
10 Jan
6 hours
26 earthquakes
VS20210201.1(19.7km)
31 Jan
23 hours
38 earthquakes
VS20210209.1(18.3km)
8 Feb
3 days 9 hours
117 earthquakes
S20210319.1(17.8km)
18 Mar
14 hours
27 earthquakes
S20210605.1(19.0km)
4 Jun
19 days 4 hours
2347 earthquakes
11 Jun
4 hours
26 earthquakes
S20210823.1(20.8km)
23 Aug
2 days 11 hours
48 earthquakes
2022
S20220420.1(10.4km)
19 Apr
3 days 1 hours
71 earthquakes
VS20220921.2(19.1km)
20 Sep
23 hours
39 earthquakes
2023
VS20230430.1(21.6km)
30 Apr
17 hours
68 earthquakes
VS20231003.1(14.0km)
3 Oct
1 day 11 hours
29 earthquakes
VS20231209.1(19.5km)
9 Dec
18 hours
34 earthquakes
2024
10 Feb
1 day 21 hours
26 earthquakes
S20240212.1(28.2km)
12 Feb
3 days 2 hours
363 earthquakes
S20240214.3(10.5km)
14 Feb
1 day 12 hours
31 earthquakes
18 May
2 days 19 hours
306 earthquakes
VS20241220.1(20.2km)
20 Dec
12 hours
48 earthquakes
2025
S20250101.1(29.9km)
1 Jan
2 hours
28 earthquakes
VS20250410.1(19.9km)
10 Apr
1 day 9 hours
64 earthquakes
S20250422.1(17.1km)
22 Apr
10 hours
28 earthquakes
VS20250711.1(18.0km)
11 Jul
1 day 18 hours
132 earthquakes
2026
S20260115.1(25.8km)
15 Jan
1 day 18 hours
81 earthquakes
9 May
4 days 16 hours
477 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm S20101215.1 Near Westmorland, California: Event Analysis and Regional Context

Seismic swarm S20101215.1 occurred 7 km east-northeast of Westmorland in Imperial County, California. The sequence began at 14:09 on 15 December 2010 and concluded at 18:59 on 16 December 2010, spanning 28 hours and 50 minutes. During this period, 101 earthquakes were recorded.

Analysis of the first 100 events reveals a typical swarm pattern of clustered, low-to-moderate magnitude activity without a single dominant mainshock. Magnitudes ranged from 1.0 to 4.3, with the largest event (magnitude 4.3) occurring at 19:16:47 on 15 December at a depth of 13 km. Depths were predominantly between 5 km and 11 km, consistent with shallow crustal faulting in the region. Multiple events clustered between 19:00 and 20:00 on 15 December, including magnitudes of 3.6, 2.8, 3.4, and 3.8, indicating episodic energy release along local fault structures.

The Imperial Valley lies within the Salton Trough, a tectonically active pull-apart basin formed by the interaction of the San Andreas Fault system and the Imperial Fault. This setting produces frequent earthquake swarms driven by right-lateral strike-slip motion and associated normal faulting. Westmorland sits near the Brawley Seismic Zone, where swarm activity is common due to fluid migration and stress transfer in the crust.

Historical records show 33 swarms in the area since 1 January 2000. Yearly distribution includes two swarms in 2000, one in 2002, four in 2003, one in 2004, three in 2005, four in 2008, nine in 2009, and nine in 2010. These sequences underscore the persistent seismic character of the Imperial Valley without progression to larger mainshock-aftershock sequences.

The S20101215.1 swarm fits established patterns of short-duration, high-event-count activity typical of the Brawley Seismic Zone. Depths and magnitudes align with shallow brittle failure in the regional fault network.

References

SeismoSight internal swarm classification S20101215.1 dataset.
United States Geological Survey regional tectonic summaries for the Imperial Valley.