Location:

Period:

2 Mar 2010 04:09:28 - 3 Mar 2010 17:44:25 (1 day 13 hours 34 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

M 7.0+:

M 8.8; 2010 Maule, Chile Earthquake; (27 Feb 2010) (49km from the swarm center)

12 swarms found nearby.

2010

PS20100227.2(50.0km)

27 Feb

2 days 9 hours

41 earthquakes

PS20100227.5(198.3km)

27 Feb

3 days 19 hours

62 earthquakes

PS20100227.1(171.6km)

27 Feb

15 hours

22 earthquakes

PS20100227.4(193.9km)

27 Feb

7 hours

11 earthquakes

PS20100227.6(36.5km)

27 Feb

13 hours

10 earthquakes

PS20100305.2(90.5km)

5 Mar

1 day 5 hours

7 earthquakes

PS20100310.1(33.5km)

10 Mar

6 hours

5 earthquakes

PS20100313.1(73.6km)

13 Mar

17 hours

6 earthquakes

PS20100316.1(12.0km)

15 Mar

16 hours

5 earthquakes

2011

PS20110211.1(54.3km)

11 Feb

5 hours

7 earthquakes

2015

PS20150319.1(61.1km)

18 Mar

14 hours

5 earthquakes

2019

S20190930.1(109.1km)

29 Sep

23 hours

28 earthquakes

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Seismic Swarm PS20100302.1: Post-Mainshock Activity Near Quirihue, Chile

Seismic swarm PS20100302.1 was recorded in central Chile, centered 79 km west-northwest of Quirihue. The sequence began at 04:09 on 2 March 2010 and concluded at 17:44 on 3 March 2010, spanning 37 hours and 34 minutes. Seven earthquakes were detected during this interval, with magnitudes between 4.7 and 6.1 and focal depths ranging from 20 km to 42 km.

The event sequence opened with a magnitude 5.4 earthquake at 04:09:28 on 2 March at 35 km depth, followed closely by a magnitude 5.5 event at 04:28:45, also at 35 km. Additional events occurred at 12:16:34 (magnitude 5.2, 35 km), 18:30:21 (magnitude 5.1, 35 km), 21:23:19 (magnitude 4.7, 42 km), and 21:44:36 (magnitude 5.0, 32 km). The swarm culminated in a magnitude 6.1 earthquake at 17:44:25 on 3 March at a shallower depth of 20 km.

This activity took place in the Maule region of Chile, part of the Peru-Chile Trench subduction zone where the Nazca Plate converges with the South American Plate at a rate of approximately 6–7 cm per year. The tectonic setting produces frequent intermediate-depth and shallow crustal seismicity. Depths recorded during the swarm align with typical patterns of interplate and intraplate faulting in this margin.

The swarm occurred five days after the magnitude 8.8 Maule earthquake of 27 February 2010, whose epicenter lay 49 km from the swarm centroid. The 2010 mainshock released extensive stress along the plate interface and triggered widespread aftershock sequences. Swarm PS20100302.1 represents the first of five swarms documented in the region since 1 January 2000, highlighting episodic clustered seismicity following major subduction events.

Such swarms typically reflect fluid migration or stress redistribution along subsidiary faults rather than a single through-going rupture. The progressive shallowing of focal depths toward the final magnitude 6.1 event suggests possible upward migration of activity within the overriding plate.

References

SeismoSight internal classification data for swarm PS20100302.1.
USGS Earthquake Catalog for regional tectonic context and 2010 Maule mainshock parameters.