Location:

Period:

8 Jan 2010 04:29:08 - 9 Jan 2010 11:59:15 (1 day 7 hours 30 minutes)

Volcanoes in 100km radius:

Kavachi(36km), Unnamed(46km), Coleman Seamount(69km), Kana Keoki(87km)

Earthquakes:

M 7.0+:

M 7.1; 94 km SE of Gizo, Solomon Islands; (3 Jan 2010) (57km from the swarm center)

4 swarms found nearby.

2004

PS20040828.1(58.3km)

28 Aug

7 hours

5 earthquakes

2007

PS20070401.1(57.6km)

1 Apr

2 days 0 hours

20 earthquakes

2010

PS20100103.1(20.5km)

3 Jan

2 days 7 hours

23 earthquakes

PS20100119.1(37.8km)

18 Jan

1 hours

5 earthquakes

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Seismic Swarm PS20100109.1: Analysis of Earthquake Activity Southeast of Gizo, Solomon Islands

A seismic swarm designated PS20100109.1 occurred southeast of Gizo in the Solomon Islands between 04:29 on 8 January 2010 and 11:59 on 9 January 2010. Over 31 hours and 30 minutes, eight earthquakes were recorded in this tectonically active region. The swarm events ranged in magnitude from 4.5 to 6.2, with depths primarily between 12 and 35 km.

The sequence began with a magnitude 5.0 event at 23 km depth on 8 January at 04:29:08. Subsequent shocks included magnitudes 5.2 and 5.0 at 35 km depth later that day, followed by a 5.1 event at 30 km. On 9 January, activity continued with a 4.5 magnitude quake at 35 km, culminating in the largest event of magnitude 6.2 at a shallower depth of 12 km. Additional events of 5.3 and 5.0 magnitudes at 35 km depth concluded the swarm. These clustered occurrences highlight typical swarm behavior, where multiple moderate events unfold without a single dominant mainshock.

The Solomon Islands occupy a complex tectonic setting within the Pacific Ring of Fire. This archipelago lies at the convergent boundary between the Pacific Plate and the Australian Plate, where subduction along the New Britain Trench and adjacent systems drives intense seismicity. The crust in this area features rapid plate convergence rates exceeding 10 cm per year, resulting in frequent earthquakes and volcanic activity. Historical records indicate that the region has experienced significant events, including the devastating 2007 magnitude 8.1 earthquake near Gizo, which generated a tsunami and caused widespread damage.

Since 2000, three swarms have been documented in the vicinity, occurring in 2004, 2007, and 2010. This 2010 swarm followed closely after a magnitude 7.1 earthquake on 3 January 2010, located 94 km southeast of Gizo and approximately 57 km from the swarm center. Such proximity suggests possible stress transfer within the subduction zone, though swarm dynamics often involve fluid migration or localized fault interactions rather than direct aftershock sequences.

Insights from the swarm reveal a pattern of moderate-magnitude events at varying depths, with the shallow 6.2 magnitude shock standing out amid deeper activity. This distribution aligns with the region's known seismogenic zone, where brittle failure occurs from the surface to around 40 km depth due to the downgoing slab. Monitoring such clusters aids in understanding regional stress accumulation along the plate interface.

References

USGS Earthquake Catalog (earthquake.usgs.gov)
Global CMT Catalog (globalcmt.org)
Pacific Tsunami Warning Center historical reports