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Note:This page contains AI-generated content for informational and entertainment purposes only. It may contain inaccuracies. Raw event data is from USGS and EMSC. All statistics, lists, and derived information are generated by this site. Full disclaimerFound an error?
Location:
0 km SE of Carnelian Bay, California
Period:
18 Sep 2023 04:17:37 - 18 Sep 2023 19:19:58 (15 hours 2 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
41
28 swarms found nearby.
2003
3 Oct
1 day 20 hours
34 earthquakes
S20031009.1(20.2km)
8 Oct
2 days 19 hours
40 earthquakes
22 Nov
2 days 23 hours
36 earthquakes
2004
S20040603.1(18.1km)
2 Jun
8 days 0 hours
197 earthquakes
S20040612.1(23.5km)
12 Jun
1 day 20 hours
35 earthquakes
2005
21 May
1 day 10 hours
39 earthquakes
S20050626.1(21.5km)
26 Jun
4 days 0 hours
149 earthquakes
S20050918.1(13.0km)
17 Sep
2 days 13 hours
34 earthquakes
7 Dec
2 days 20 hours
40 earthquakes
2007
8 May
2 days 16 hours
36 earthquakes
2008
S20081121.2(16.8km)
21 Nov
1 day 17 hours
26 earthquakes
2010
S20101204.1(28.7km)
3 Dec
1 day 22 hours
32 earthquakes
2012
S20120408.2(14.6km)
8 Apr
2 days 17 hours
45 earthquakes
S20120623.1(12.7km)
22 Jun
1 day 13 hours
37 earthquakes
S20120627.1(13.1km)
26 Jun
3 days 22 hours
58 earthquakes
2013
S20130325.1(29.4km)
24 Mar
1 day 1 hours
36 earthquakes
2014
3 Apr
1 day 13 hours
40 earthquakes
S20140623.1(15.1km)
22 Jun
1 day 19 hours
28 earthquakes
2015
S20150408.1(15.9km)
8 Apr
2 days 9 hours
57 earthquakes
2016
S20160319.2(17.0km)
18 Mar
20 hours
29 earthquakes
S20161124.1(29.9km)
23 Nov
2 days 6 hours
34 earthquakes
2017
S20170729.1(14.8km)
29 Jul
14 hours
26 earthquakes
2018
S20180528.1(24.5km)
27 May
20 hours
24 earthquakes
26 Jul
1 day 8 hours
40 earthquakes
2019
S20190911.1(20.5km)
11 Sep
18 hours
26 earthquakes
2021
S20210426.1(11.6km)
25 Apr
3 days 1 hours
45 earthquakes
S20210528.2(12.0km)
28 May
16 hours
33 earthquakes
2024
S20240721.2(10.8km)
20 Jul
1 day 13 hours
51 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm Near Carnelian Bay, California: September 18, 2023 Event Analysis

A seismic swarm designated S20230918.1 occurred 0 km southeast of Carnelian Bay, California, on September 18, 2023. The sequence began at 04:17 UTC and concluded at 19:19 UTC, spanning 15 hours and 2 minutes. During this period, 41 earthquakes were recorded.

Carnelian Bay lies on the northern shore of Lake Tahoe within the Sierra Nevada range. The region forms part of the Walker Lane belt, a zone of distributed shear accommodating right-lateral motion between the Pacific and North American plates. Active normal and strike-slip faults in the Tahoe-Sierra frontal fault system drive shallow crustal seismicity. Earthquake depths in this setting commonly range from 1 to 8 km, consistent with the observed swarm data.

The swarm exhibited typical characteristics of clustered microseismicity without a dominant mainshock-aftershock pattern. Magnitudes ranged from -0.3 to 3.2, with the largest event occurring at 04:17:37 UTC at a depth of 3 km. Two additional events exceeded magnitude 2.0, including a 2.5 at 08:04:48 UTC (depth 1 km) and a 2.4 at 15:14:54 UTC (depth 4 km). The majority of events clustered between 6 and 8 km depth, indicating a compact source volume.

Historical records indicate 27 swarms in the same area since January 1, 2000. Annual counts include three swarms in 2003, four in 2005, three in 2012, and two each in 2014, 2016, 2018, and 2021. This frequency underscores the persistent tectonic strain release along local fault structures.

Such swarms contribute to long-term seismic hazard assessment in the Lake Tahoe basin. They reflect episodic fluid migration or aseismic slip along faults rather than magmatic processes. Monitoring data from regional networks continue to refine models of fault segmentation and recurrence intervals for larger events in the Walker Lane.

References

SeismoSight internal swarm classification S20230918.1
USGS Earthquake Hazards Program regional tectonic summaries
California Geological Survey fault database for the Tahoe basin