Location:

Period:

4 Jan 2002 01:47:44 - 9 Jan 2002 22:59:59 (5 days 21 hours 12 minutes)

Volcanoes in 100km radius:

Prieto, Cerro(19km), Salton Buttes(99km)

Earthquakes:

156

16 swarms found nearby.

2000

S20000502.1(28.9km)

1 May

4 days 19 hours

60 earthquakes

VS20001102.1(24.5km)

2 Nov

2 days 22 hours

63 earthquakes

2002

S20020222.1(27.2km)

22 Feb

6 days 19 hours

453 earthquakes

S20020303.1(26.9km)

2 Mar

4 days 12 hours

88 earthquakes

2005

VS20050510.1(21.7km)

9 May

9 days 8 hours

196 earthquakes

2006

S20060528.1(14.0km)

27 May

1 day 14 hours

27 earthquakes

2008

VS20080209.1(19.3km)

9 Feb

19 days 1 hours

830 earthquakes

S20080626.1(27.2km)

25 Jun

21 hours

27 earthquakes

VS20081120.1(23.5km)

20 Nov

2 days 0 hours

35 earthquakes

2009

S20090920.1(17.4km)

19 Sep

2 days 5 hours

46 earthquakes

S20091230.1(14.5km)

30 Dec

2 days 18 hours

112 earthquakes

2010

PS20100405.1(30.0km)

4 Apr

1 hours

5 earthquakes

S20100724.3(30.0km)

24 Jul

9 days 17 hours

117 earthquakes

2024

S20240512.1(12.9km)

12 May

2 days 10 hours

93 earthquakes

S20240605.1(7.6km)

5 Jun

13 hours

25 earthquakes

S20241009.2(23.9km)

8 Oct

22 hours

25 earthquakes

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Seismic Swarm S20020104.2: Analysis of Activity Near Delta, Baja California

Seismic swarm S20020104.2 was recorded from 01:47 on 4 January 2002 until 22:59 on 9 January 2002, spanning 141 hours and 12 minutes. The events occurred 15 km northeast of Delta, Baja California, Mexico, with a total of 156 earthquakes detected.

The swarm took place in the Mexicali Valley, a tectonically active zone at the boundary between the Pacific and North American plates. This region features a network of strike-slip faults, including the Imperial Fault and the Cerro Prieto Fault, which accommodate right-lateral shear as part of the broader San Andreas transform system. Shallow seismicity is common, often linked to geothermal activity and fluid migration within the crust. Depths of recorded events clustered between 6 and 7 km, consistent with the brittle upper crust in this extensional-transform setting.

Analysis of the first 100 events shows magnitudes ranging from 1.7 to 3.5, with the majority falling between 1.8 and 2.8. Depths remained stable at 6–7 km throughout. Activity began with a modest event of magnitude 1.9 at 01:47 on 4 January, followed by a rapid increase in frequency later that day. Peak intensity occurred between 17:00 and 23:00 on 4 January, when multiple events of magnitude 2.8–3.5 were recorded, including the swarm’s largest shocks of 3.5. Subsequent days exhibited a gradual decline in both rate and maximum magnitude, with events of 3.0–3.4 still occurring on 5 and 6 January before tapering off.

This pattern aligns with historical swarm behavior in the Imperial Valley, where sequences of small to moderate events often occur without a single dominant mainshock. The 2002 swarm represents the second such episode since 1 January 2000, following an earlier swarm in 2000. Such recurrent swarms reflect ongoing tectonic strain release along the plate boundary.

References

USGS Earthquake Catalog
Geological Survey of Mexico (SGM) regional tectonic reports
SeismoSight internal swarm classification S20020104.2