Location:

Period:

5 Mar 2023 01:52:49 - 6 Mar 2023 04:50:20 (1 day 2 hours 57 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

31 swarms found nearby.

2003

S20030306.1(21.9km)

5 Mar

1 day 2 hours

35 earthquakes

2009

S20090726.1(24.6km)

25 Jul

1 day 19 hours

29 earthquakes

2011

S20110202.2(21.6km)

1 Feb

1 day 18 hours

43 earthquakes

2014

S20140127.1(17.0km)

26 Jan

2 days 4 hours

38 earthquakes

S20140418.1(28.3km)

18 Apr

8 days 7 hours

191 earthquakes

S20140510.1(15.1km)

9 May

2 days 9 hours

44 earthquakes

2015

S20150211.2(21.9km)

10 Feb

12 days 21 hours

168 earthquakes

2016

S20160614.1(16.2km)

14 Jun

7 days 5 hours

80 earthquakes

S20161221.1(21.1km)

21 Dec

1 day 21 hours

34 earthquakes

2017

S20170609.1(16.8km)

8 Jun

3 days 22 hours

61 earthquakes

S20170926.1(21.5km)

25 Sep

124 days 21 hours

2217 earthquakes

2018

S20180203.1(29.5km)

2 Feb

28 days 21 hours

426 earthquakes

S20180527.1(22.3km)

26 May

4 days 20 hours

54 earthquakes

2020

S20200109.1(25.6km)

8 Jan

11 days 9 hours

159 earthquakes

S20200202.1(24.5km)

1 Feb

8 days 17 hours

147 earthquakes

S20200301.1(13.1km)

29 Feb

6 days 16 hours

67 earthquakes

S20200305.1(22.9km)

5 Mar

10 hours

27 earthquakes

S20200526.3(26.8km)

25 May

7 days 18 hours

100 earthquakes

S20200607.1(29.9km)

6 Jun

9 days 19 hours

109 earthquakes

S20200926.2(24.1km)

25 Sep

3 days 10 hours

42 earthquakes

S20201219.1(15.7km)

18 Dec

5 days 0 hours

66 earthquakes

2021

S20210328.1(22.1km)

27 Mar

2 days 21 hours

33 earthquakes

S20210427.1(20.9km)

26 Apr

5 days 5 hours

80 earthquakes

S20210921.1(24.7km)

20 Sep

8 days 7 hours

216 earthquakes

2022

S20220419.1(14.7km)

18 Apr

8 days 1 hours

76 earthquakes

S20220702.1(20.7km)

1 Jul

3 days 23 hours

49 earthquakes

S20221026.1(23.3km)

25 Oct

1 day 10 hours

35 earthquakes

2023

S20230221.1(27.2km)

20 Feb

1 day 17 hours

25 earthquakes

S20230326.1(24.8km)

25 Mar

2 days 6 hours

38 earthquakes

2024

S20240829.1(24.3km)

28 Aug

2 days 1 hours

31 earthquakes

2025

S20251128.1(16.7km)

28 Nov

7 days 2 hours

82 earthquakes

AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm S20230305.1: Activity Near San Jacinto, California

A seismic swarm designated S20230305.1 occurred 3 km southeast of San Jacinto, California, beginning at 01:52 on 5 March 2023 and concluding at 04:50 on 6 March 2023. Over this 26-hour, 57-minute period, 25 earthquakes were recorded. The events clustered tightly in both time and space, with the majority occurring within the first 24 hours.

All recorded events registered low magnitudes, ranging from 0.4 to 1.7. The largest shock measured 1.7 and took place at 09:38 on 5 March. Depths remained consistent between 12 km and 17 km, with most events centered near 14 km. This narrow depth range and modest energy release are characteristic of swarm behavior rather than a mainshock-aftershock sequence.

The San Jacinto region lies within the San Jacinto Fault Zone, a major component of the southern San Andreas Fault system. This right-lateral strike-slip fault accommodates a substantial fraction of Pacific-North American plate motion and exhibits one of the highest slip rates in California. The fault zone has produced numerous moderate to large earthquakes historically and continues to generate frequent small events and occasional swarms due to its complex geometry and interaction with adjacent structures.

Since 1 January 2000, 28 swarms have been identified in the immediate area. Earlier episodes occurred in 2003, 2009, and 2011. Activity increased notably after 2014, with three swarms that year, followed by additional clusters in 2015, 2016 (two), 2017 (two), 2018 (two), 2020 (eight), 2021 (three), 2022 (three), and the current 2023 event. This temporal pattern indicates persistent background seismicity punctuated by episodic swarm activity.

Swarm S20230305.1 fits within the established seismic character of the San Jacinto Fault Zone. The shallow-to-intermediate depths and low magnitudes suggest fluid migration or aseismic slip processes may have contributed to the clustered triggering, though definitive mechanisms require further geophysical analysis. No damage or felt reports were associated with these microearthquakes.

Ongoing monitoring by regional seismic networks remains essential for tracking potential escalation along this high-hazard fault segment.

References:
USGS Earthquake Catalog
California Geological Survey Fault Database
Southern California Seismic Network Annual Reports