Location:

Period:

16 Nov 2018 03:26:55 - 16 Nov 2018 21:19:45 (17 hours 52 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

M 7.0+:

M 7.0; Solomon Islands; (9 Nov 2004) (51km from the swarm center)

6 swarms found nearby.

2004

PS20041112.1(178.7km)

11 Nov

1 day 1 hours

7 earthquakes

2005

PS20050306.2(58.0km)

6 Mar

15 hours

6 earthquakes

2008

PS20080719.1(158.2km)

19 Jul

2 hours

6 earthquakes

2013

PS20130213.1(140.0km)

12 Feb

16 hours

6 earthquakes

2014

PS20140412.1(171.6km)

12 Apr

1 day 20 hours

26 earthquakes

2015

PS20150522.1(68.7km)

22 May

2 hours

7 earthquakes

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Seismic Swarm PS20181116.2: Analysis of Activity East of Kirakira, Solomon Islands

Seismic swarm PS20181116.2 occurred in a tectonically active zone 151 km east of Kirakira in the Solomon Islands. The sequence began at 03:26 on 16 November 2018 and concluded at 21:19 the same day, lasting 17 hours and 52 minutes. Five earthquakes were recorded during this period, with all events originating at a shallow depth of 10 km. The swarm included a mainshock of magnitude 6.2, followed by events of magnitudes 5.0, 5.0, 5.2, and 4.5.

This activity aligns with the broader tectonic setting of the Solomon Islands, which lie along the convergent boundary between the Pacific Plate and the Australian Plate. The region forms part of the Pacific Ring of Fire, where subduction processes generate frequent seismic events. Shallow depths around 10 km are characteristic of crustal deformation in this arc system, often linked to stress release along fault networks associated with the subduction interface.

Historical records indicate six prior swarms in the area since 1 January 2000, occurring in 2004, 2005, 2008, 2013, 2014, and 2015. These episodes demonstrate recurring clustered seismicity rather than isolated mainshock-aftershock sequences. A magnitude 7.0 earthquake struck on 9 November 2004 approximately 51 km from the center of swarm PS20181116.2, underscoring the potential for larger events in proximity to swarm locations.

Swarm events like PS20181116.2 provide insight into episodic stress migration within the plate boundary zone. The rapid succession of moderate-magnitude quakes at consistent shallow depths suggests fluid involvement or localized fault slip, common in subduction-related environments. Such patterns contribute to understanding regional seismic hazard, where multiple moderate events can occur without immediate escalation to great earthquakes.

The Solomon Islands have experienced repeated seismic activity due to ongoing plate convergence at rates exceeding 10 cm per year in segments of the boundary. This dynamic drives both swarm-type clustering and larger thrust events, shaping the long-term geological evolution of the island arc.

References

SeismoSight internal swarm classification data for PS20181116.2 and historical statistics.
Tectonic framework of the Solomon Islands arc from standard geological surveys of Pacific-Australian plate interaction.