M 7.9; 140 km E of Kokopo, Papua New Guinea; (17 Dec 2016) (47km from the swarm center)
M 7.5; 53 km SE of Kokopo, Papua New Guinea; (29 Mar 2015) (66km from the swarm center)
M 7.6; 135 km E of Kokopo, Papua New Guinea; (9 Sep 2005) (42km from the swarm center)
M 7.8; 135 km SE of Kokopo, Papua New Guinea; (16 Nov 2000) (85km from the swarm center)
M 7.0; 191 km ESE of Kokopo, Papua New Guinea; (29 Oct 2000) (99km from the swarm center)
Seismic Swarm PS20001208.1: Analysis of Activity East of Kokopo, Papua New Guinea
Seismic swarm PS20001208.1 was recorded 80 km east of Kokopo, Papua New Guinea, beginning at 01:40 on 7 December 2000 and concluding at 15:24 on 8 December 2000. Over 37 hours and 43 minutes, seven earthquakes were detected, with magnitudes ranging from 4.7 to 5.8 and all events occurring at a focal depth of 33 km. The sequence began with a magnitude 5.0 event, followed by a peak magnitude 5.8 shock later that morning. Subsequent events included magnitudes 5.4, 5.1, and another 5.4 on 7 December, then a magnitude 4.7 and a final magnitude 5.5 on 8 December.
This swarm unfolded within the tectonically complex New Britain region, where the Pacific Ring of Fire exhibits intense activity driven by the subduction of the Solomon Sea Plate beneath the South Bismarck Plate. The resulting compressional forces generate frequent intermediate-depth seismicity along the arc, consistent with the uniform 33 km depths observed in the swarm. Papua New Guinea's eastern islands experience elevated seismic rates due to this plate interaction, which also fuels volcanic systems such as those near Rabaul.
Since 1 January 2000, six swarms have been documented in the broader area, with PS20001208.1 representing the earliest recorded instance. The region has also hosted several major earthquakes in the same period, including a magnitude 7.8 event 85 km from the swarm center on 16 November 2000, a magnitude 7.6 shock 42 km away on 9 September 2005, and a magnitude 7.9 event 47 km distant on 17 December 2016. Additional strong events comprise a magnitude 7.5 quake 66 km from the center on 29 March 2015, a magnitude 7.6 event 71 km away on 14 May 2019, and a magnitude 7.0 shock 99 km distant on 29 October 2000. These occurrences underscore the persistent seismic hazard along the arc.
Swarm sequences such as PS20001208.1 provide insight into localized stress release without progression to larger mainshock-aftershock patterns. The clustered timing and moderate magnitudes reflect fluid migration or minor fault adjustments within the subduction interface, common in this geological setting. Continued monitoring remains essential given the area's history of both swarms and great earthquakes.
USGS Earthquake Catalog
SeismoSight Internal Swarm Database