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Location:
12km SE of Anza, CA
Period:
2 Dec 2010 12:08:20 - 12 Dec 2010 12:58:36 (10 days 50 minutes)
Volcanoes in 100km radius:
Salton Buttes(91km)
Earthquakes:
68
79 swarms found nearby.
2001
31 Oct
10 days 17 hours
471 earthquakes
2002
2 Jan
3 days 5 hours
53 earthquakes
23 Oct
2 days 17 hours
38 earthquakes
2003
S20030306.1(25.9km)
5 Mar
1 day 2 hours
35 earthquakes
S20031113.1(18.9km)
12 Nov
1 day 17 hours
31 earthquakes
2005
12 Jun
26 days 19 hours
904 earthquakes
19 Aug
3 days 23 hours
96 earthquakes
2009
S20090726.1(23.2km)
25 Jul
1 day 19 hours
29 earthquakes
S20090818.1(27.5km)
17 Aug
1 day 21 hours
39 earthquakes
2010
8 Feb
3 days 22 hours
44 earthquakes
S20100405.7(10.5km)
5 Apr
5 days 18 hours
62 earthquakes
S20100613.1(15.4km)
12 Jun
9 days 5 hours
239 earthquakes
7 Jul
35 days 19 hours
1709 earthquakes
2011
S20110202.2(26.3km)
1 Feb
1 day 18 hours
43 earthquakes
18 Mar
1 day 23 hours
34 earthquakes
15 Apr
7 days 6 hours
90 earthquakes
26 Jul
4 days 1 hours
42 earthquakes
2012
20 May
4 days 2 hours
45 earthquakes
21 Jun
3 days 19 hours
39 earthquakes
29 Jun
2 days 0 hours
31 earthquakes
2013
10 Mar
72 days 2 hours
2118 earthquakes
S20130920.1(21.7km)
19 Sep
1 day 10 hours
31 earthquakes
21 Sep
8 days 10 hours
91 earthquakes
30 Dec
8 days 18 hours
91 earthquakes
2014
S20140418.1(21.9km)
18 Apr
8 days 7 hours
191 earthquakes
7 Aug
1 day 13 hours
28 earthquakes
2015
S20150211.2(25.6km)
10 Feb
12 days 21 hours
168 earthquakes
31 Mar
38 days 7 hours
543 earthquakes
2016
9 Jun
33 days 4 hours
1773 earthquakes
19 Jul
6 days 5 hours
68 earthquakes
25 Oct
5 days 21 hours
73 earthquakes
S20161221.1(27.7km)
21 Dec
1 day 21 hours
34 earthquakes
29 Dec
4 days 7 hours
48 earthquakes
2017
S20170503.1(22.4km)
2 May
5 days 5 hours
91 earthquakes
S20170510.1(22.3km)
9 May
15 days 6 hours
129 earthquakes
S20170727.1(23.4km)
26 Jul
14 days 9 hours
192 earthquakes
S20170907.1(22.9km)
6 Sep
14 days 21 hours
245 earthquakes
S20170926.1(26.9km)
25 Sep
124 days 21 hours
2217 earthquakes
9 Nov
2 days 20 hours
44 earthquakes
2018
S20180203.1(18.5km)
2 Feb
28 days 21 hours
426 earthquakes
S20180305.1(16.5km)
4 Mar
19 days 17 hours
203 earthquakes
S20180314.1(14.7km)
13 Mar
1 day 13 hours
26 earthquakes
S20180403.1(22.2km)
2 Apr
10 days 14 hours
197 earthquakes
S20180420.1(23.9km)
19 Apr
69 days 21 hours
1109 earthquakes
S20180527.1(27.3km)
26 May
4 days 20 hours
54 earthquakes
S20180630.1(21.0km)
29 Jun
41 days 14 hours
582 earthquakes
S20180811.1(20.1km)
11 Aug
209 days 15 hours
6032 earthquakes
2019
S20190328.1(23.9km)
27 Mar
5 days 20 hours
79 earthquakes
S20190426.1(20.4km)
25 Apr
1 day 22 hours
37 earthquakes
2020
S20200109.1(24.3km)
8 Jan
11 days 9 hours
159 earthquakes
S20200122.1(23.3km)
21 Jan
3 days 12 hours
57 earthquakes
S20200202.1(23.2km)
1 Feb
8 days 17 hours
147 earthquakes
4 Apr
40 days 3 hours
2928 earthquakes
S20200526.3(23.0km)
25 May
7 days 18 hours
100 earthquakes
2 Jun
2 days 12 hours
63 earthquakes
S20200607.1(23.7km)
6 Jun
9 days 19 hours
109 earthquakes
S20200703.1(23.0km)
2 Jul
3 days 16 hours
70 earthquakes
S20200708.1(23.5km)
7 Jul
26 days 8 hours
287 earthquakes
S20200926.2(24.0km)
25 Sep
3 days 10 hours
42 earthquakes
25 Sep
2 days 2 hours
44 earthquakes
2021
S20210328.1(25.7km)
27 Mar
2 days 21 hours
33 earthquakes
S20210427.1(26.7km)
26 Apr
5 days 5 hours
80 earthquakes
S20210609.1(23.6km)
8 Jun
5 days 16 hours
126 earthquakes
S20210921.1(22.8km)
20 Sep
8 days 7 hours
216 earthquakes
2022
13 Jan
4 days 5 hours
157 earthquakes
18 May
1 day 8 hours
29 earthquakes
S20220702.1(26.8km)
1 Jul
3 days 23 hours
49 earthquakes
S20220714.1(22.0km)
13 Jul
1 day 12 hours
26 earthquakes
S20220825.1(25.7km)
25 Aug
1 day 3 hours
27 earthquakes
22 Sep
1 day 18 hours
31 earthquakes
29 Sep
4 days 5 hours
69 earthquakes
S20221026.1(24.3km)
25 Oct
1 day 10 hours
35 earthquakes
S20221231.1(18.6km)
31 Dec
2 days 20 hours
86 earthquakes
2023
S20230221.1(22.7km)
20 Feb
1 day 17 hours
25 earthquakes
S20230326.1(23.8km)
25 Mar
2 days 6 hours
38 earthquakes
2024
S20240621.1(13.6km)
20 Jun
3 days 0 hours
41 earthquakes
S20240829.1(23.1km)
28 Aug
2 days 1 hours
31 earthquakes
2025
S20250516.1(18.2km)
16 May
4 days 7 hours
45 earthquakes
S20251117.1(11.0km)
16 Nov
3 days 16 hours
56 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm S20101203.2: Analysis of Activity Near Anza, California

An earthquake swarm designated S20101203.2 was recorded 12 km southeast of Anza, California. The sequence began at 12:08 on 2 December 2010 and concluded at 12:58 on 12 December 2010. Over approximately 240 hours and 50 minutes, 68 earthquakes were detected. Magnitudes ranged from 0.0 to 2.2, with the majority below 1.0. Focal depths varied between 4 km and 14 km, indicating shallow crustal activity typical of the region.

The swarm initiated with several events on 2 December, including magnitudes of 0.4, 1.1, and 1.8. Activity peaked on 3 December with multiple events reaching 2.2. Subsequent days showed declining frequency but persistent low-magnitude releases through 12 December. No single mainshock dominated the sequence; instead, events occurred in clusters without clear foreshock-aftershock patterns.

The Anza area lies within the Peninsular Ranges of southern California, part of the tectonically active boundary between the Pacific and North American plates. This location coincides with the San Jacinto Fault Zone, a major northwest-trending right-lateral strike-slip system that accommodates a significant portion of regional plate motion. The fault zone features multiple strands that have produced both historical large earthquakes and recurrent swarms. Depths recorded in the swarm align with the brittle-ductile transition zone in this segment of the fault system.

Seismic swarms in the Anza region reflect fluid migration or aseismic slip triggering brittle failure along fault segments. Historical records show 13 swarms since 1 January 2000, occurring in 2001 (1 swarm), 2002 (2), 2003 (2), 2005 (2), 2009 (2), and 2010 (4). These episodes underscore the persistent strain accumulation and release characteristic of the San Jacinto Fault Zone.

The 2010 swarm contributed to ongoing monitoring of microseismicity that helps refine fault models and assess potential for larger events. No damage or felt reports were associated with these low-magnitude events.

References

  • United States Geological Survey Earthquake Catalog
  • California Geological Survey Fault Activity Map
  • Southern California Earthquake Data Center Swarm Database