Seismic Swarm PS20001116.3: The November 2000 Earthquake Sequence East of Kokopo, Papua New Guinea

The seismic swarm designated PS20001116.3 occurred in a highly active tectonic setting 58 km east of Kokopo, Papua New Guinea. It began at 04:54 on 16 November 2000 and concluded at 10:01 on 19 November 2000, spanning 77 hours and 6 minutes. During this interval, 52 earthquakes were recorded, commencing with a major magnitude 8.0 event at 33 km depth.

The sequence featured numerous moderate-to-strong aftershocks, predominantly at 33 km depth. Notable events included a magnitude 5.2 shock at 05:46 on 16 November, followed by additional events of magnitudes 5.5, 5.3, and 5.4 throughout the day. On 17 November, activity continued with a magnitude 5.8 event at 01:37 and a magnitude 5.7 at 21:45. The largest subsequent shock reached magnitude 6.8 at 06:54 on 18 November. The swarm closed with events of magnitudes 6.0 and 6.1 on 19 November.

This swarm unfolded within the New Britain subduction zone, where the Solomon Sea Plate descends beneath the South Bismarck Plate along the New Britain Trench. The region experiences frequent seismicity due to rapid plate convergence rates exceeding 10 cm per year. Shallow to intermediate-depth earthquakes are common, reflecting both interplate thrusting and intraslab deformation.

Papua New Guinea’s eastern Bismarck Sea area has a well-documented history of large earthquakes and volcanic unrest. The nearby Rabaul caldera has produced major eruptions in 1937 and 1994. The 2000 sequence occurred amid this dynamic environment, with the magnitude 8.0 mainshock triggering extensive aftershock activity that persisted for days.

Subsequent strong events have continued to affect the broader region. These include a magnitude 7.8 earthquake on 17 November 2000 located 24 km from the swarm center, a magnitude 7.5 event in May 2015 only 16 km away, and a magnitude 7.0 shock in October 2018 situated 87 km distant. Such recurrence underscores the persistent seismic hazard along this segment of the plate boundary.

The PS20001116.3 swarm illustrates typical characteristics of post-mainshock sequences in subduction settings, where stress redistribution sustains elevated seismicity rates over several days. Depths clustered near 33 km align with the inferred megathrust interface, while the final deeper event at 57 km may reflect slab-related processes.

Data for this analysis derive from the SeismoSight internal classification of swarm PS20001116.3. Additional regional context incorporates established tectonic frameworks of the Papua New Guinea margin.

References

SeismoSight swarm classification records
USGS Earthquake Catalog (regional events)
Global CMT Project (moment tensor solutions)