Seismic Swarm PS20220910.1 Near Northern Papua, Indonesia

A seismic swarm designated PS20220910.1 occurred near the northern coast of Papua, Indonesia, between 23:31 UTC on 9 September 2022 and 00:23 UTC on 10 September 2022. The sequence lasted 52 minutes and included five earthquakes with magnitudes ranging from 4.1 to 6.2. Events were recorded at depths between 10 km and 30 km, indicating shallow crustal activity consistent with the region's active tectonic setting.

The sequence began with a magnitude 6.2 event at 23:31:47 on 9 September at 18 km depth. This was followed 12 minutes later by a magnitude 5.9 earthquake at 30 km depth. Subsequent events included a magnitude 5.0 quake at 10 km depth, another magnitude 6.2 event at 21 km depth, and a final magnitude 4.1 shock at 22 km depth. The two largest events shared similar magnitudes but occurred at slightly different depths, suggesting rupture along adjacent fault segments.

This swarm represents the fifth such cluster recorded in the area since 2000. Earlier swarms occurred once each in 2010 and 2011, with three additional clusters documented in 2019. The 2022 activity aligns with the region's history of episodic earthquake sequences rather than isolated mainshock-aftershock patterns.

Northern Papua lies within a tectonically complex zone where the Pacific Plate interacts with the Australian Plate along the New Guinea Trench and associated strike-slip faults. The area experiences frequent seismicity due to oblique convergence and crustal deformation. Historical records show strong events nearby, including a magnitude 7.0 earthquake on 27 July 2015 located 234 km west of Abepura and approximately 67 km from the 2022 swarm center. Such events underscore the potential for moderate-to-large earthquakes along the northern margin of the island.

Seismic swarms in this setting often reflect fluid migration or stress transfer along pre-existing faults within the accretionary complex. Depths recorded during the September 2022 swarm fall within the typical range for upper-crustal events in Papua, where the brittle-ductile transition occurs around 20–30 km. No surface rupture was reported, consistent with the moderate magnitudes and offshore location.

Continued monitoring remains essential given the proximity of population centers along the northern coast and the historical recurrence of both swarms and larger individual earthquakes. The 2022 sequence did not produce significant damage reports, yet it highlights the ongoing seismic hazard in one of Earth's most active plate boundary zones.

References

USGS Earthquake Catalog (earthquake.usgs.gov)
Global CMT Catalog (globalcmt.org)