Location:

Period:

18 Jan 2010 23:11:03 - 19 Jan 2010 01:00:22 (1 hour 49 minutes)

Volcanoes in 100km radius:

Kavachi(8km), Unnamed(10km), Coleman Seamount(85km)

Earthquakes:

M 7.0+:

M 7.1; 94 km SE of Gizo, Solomon Islands; (3 Jan 2010) (65km from the swarm center)

5 swarms found nearby.

2004

PS20040828.1(65.9km)

28 Aug

7 hours

5 earthquakes

2007

PS20070401.1(57.6km)

1 Apr

2 days 0 hours

20 earthquakes

2010

PS20100103.1(18.6km)

3 Jan

2 days 7 hours

23 earthquakes

PS20100109.1(37.8km)

8 Jan

1 day 7 hours

8 earthquakes

2022

PS20221122.1(195.7km)

22 Nov

1 day 5 hours

12 earthquakes

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Seismic Swarm PS20100119.1: Analysis of January 2010 Activity Southeast of Gizo, Solomon Islands

A seismic swarm designated PS20100119.1 was recorded southeast of Gizo in the Solomon Islands between 23:11 on 18 January 2010 and 01:00 on 19 January 2010. Over 1 hour and 49 minutes, five earthquakes occurred, with magnitudes ranging from 5.1 to 5.6 and focal depths between 19 km and 39 km. The swarm epicenter lies approximately 133 km southeast of Gizo.

The sequence began with a magnitude 5.2 event at 23:11:03 on 18 January at 22 km depth, followed one minute later by a magnitude 5.1 shock at 19 km depth. Two closely spaced events occurred around 00:17 on 19 January: a magnitude 5.1 at 22 km depth and the largest event of the swarm, magnitude 5.6 at 39 km depth. The final recorded earthquake was a magnitude 5.1 at 31 km depth at 01:00:22.

The Solomon Islands occupy a tectonically complex region at the convergent boundary between the Pacific Plate and the Australian Plate, with the intervening Solomon Sea Plate contributing to oblique subduction along the New Britain–San Cristobal trench system. This setting produces frequent shallow to intermediate-depth seismicity, often clustered in swarms due to stress transfer along the megathrust and associated strike-slip faults. The January 2010 swarm occurred within the forearc region where the subducting slab lies at depths consistent with the observed hypocenters.

Regional historical data indicate that four seismic swarms have been identified since 2000. These occurred in 2004 (one swarm), 2007 (one swarm), and 2010 (two swarms). A magnitude 7.1 earthquake struck 94 km southeast of Gizo on 3 January 2010, approximately 65 km from the swarm center, highlighting elevated seismic activity in the same segment of the plate boundary during early 2010.

Such swarms typically reflect transient increases in crustal stress rather than foreshock sequences leading to larger mainshocks, although they underscore the persistent seismic hazard in this segment of the arc. Depths in the 19–39 km range align with the expected seismogenic zone above the subducting slab in this part of the Solomon Islands.

References

USGS Earthquake Catalog (earthquake.usgs.gov)
Global CMT Catalog (globalcmt.org)
SeismoSight internal swarm classification records