Location:

Period:

13 Apr 2001 23:25:31 - 20 Apr 2001 09:00:05 (6 days 9 hours 34 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

135

10 swarms found nearby.

2001

S20010517.1(29.7km)

17 May

5 days 0 hours

230 earthquakes

2004

S20040328.1(25.1km)

28 Mar

4 days 0 hours

71 earthquakes

S20040402.1(24.7km)

2 Apr

1 day 9 hours

28 earthquakes

2005

S20050806.1(29.0km)

6 Aug

7 days 5 hours

120 earthquakes

2013

S20130804.1(28.7km)

4 Aug

1 day 20 hours

50 earthquakes

S20131223.1(28.0km)

23 Dec

5 days 10 hours

116 earthquakes

2019

S20190528.1(29.4km)

28 May

2 days 3 hours

61 earthquakes

S20190809.1(27.2km)

8 Aug

1 day 18 hours

60 earthquakes

S20190906.1(29.5km)

5 Sep

1 day 4 hours

27 earthquakes

2020

S20200305.2(26.7km)

5 Mar

1 day 5 hours

42 earthquakes

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Seismic Swarm S20010414.1: Analysis of Activity Near Kernville, California

The seismic swarm designated S20010414.1 occurred 26 km NNE of Kernville, California, beginning at 23:25 on 13 April 2001 and concluding at 09:00 on 20 April 2001. Over 153 hours and 34 minutes, the sequence produced 135 earthquakes. This event cluster exemplifies swarm behavior common in the southern Sierra Nevada, where numerous small-magnitude events occur without a dominant mainshock.

The first 100 events, recorded between 13 and 17 April, displayed consistent shallow focal depths predominantly at 3 km, with occasional occurrences at 4 km and 5 km. Magnitudes ranged from 0.0 to 3.7. The sequence initiated with a magnitude 2.0 event at 23:25:31 on 13 April. Activity intensified on 14 April, featuring a peak magnitude 3.7 earthquake at 14:51:22, followed rapidly by a 3.0 event and multiple shocks between 2.5 and 2.8. Subsequent events maintained a pattern of frequent low-to-moderate magnitudes, with notable repetitions around 2.5–2.7. By 15 April, the rate remained elevated but gradually declined, including isolated magnitude 2.6 and 3.0 events on 16 and 17 April.

This temporal distribution indicates a rapid onset followed by sustained aftershock-like productivity over several days, typical of fluid-driven or stress-transfer mechanisms in the crust. Depths clustered tightly near 3 km suggest activation within the upper brittle crust, consistent with regional fault structures.

The Kernville area lies within the southern Sierra Nevada, underlain by Mesozoic granitic rocks of the Sierra Nevada Batholith. The regional geology features north-northwest trending faults, including segments of the Kern Canyon Fault system, which accommodate minor dextral shear and extension. Historical seismicity in the broader Kern County region includes the major 1952 Mw 7.3 event south of the swarm location, along with recurrent moderate swarms attributed to the same tectonic regime. Updated monitoring by the USGS confirms ongoing low-level activity in the area, with no significant large-magnitude events recorded since 2001 in the immediate swarm vicinity.

The 2001 swarm contributed to understanding of distributed deformation in the southern Sierra, where small events help release accumulated strain without producing surface rupture. Depths and magnitudes align with background seismicity patterns observed through modern networks.

References

USGS Earthquake Catalog California Geological Survey Regional Fault Maps SeismoSight Internal Swarm Classification S20010414.1