Seismic Swarm PS20100616.1 Near Biak, Indonesia

Seismic swarm PS20100616.1 was recorded 147 km south-southeast of Biak, Indonesia. The sequence began at 03:06 on 16 June 2010 and concluded at 06:10 the same day, encompassing six earthquakes over three hours and four minutes.

The individual events unfolded as follows. At 03:06:02, a magnitude 6.2 earthquake occurred at 13 km depth. Eleven minutes later, at 03:16:27, a magnitude 7.0 event struck at 18 km depth. Subsequent shocks included a magnitude 5.0 at 03:24:24 (10 km depth), a magnitude 5.2 at 03:38:14 (10 km depth), a magnitude 6.6 at 03:58:08 (10 km depth), and a final magnitude 5.0 at 06:10:44 (10 km depth).

This activity aligns with the region’s established pattern of clustered seismicity. Since 1 January 2000, three swarms have been documented in the vicinity, with the earliest occurring in 2004. The magnitude 7.0 event of 16 June 2010, located 121 km south-southeast of Biak and 15 km from the swarm centroid, represents one of the stronger shocks recorded in the area during this period.

Biak lies within the tectonically complex collision zone between the Australian and Pacific plates. Convergence along the New Guinea Trench and associated strike-slip faults produces frequent moderate-to-large earthquakes. The shallow focal depths observed in the swarm are consistent with crustal deformation in this setting. Historical records confirm elevated seismic hazard, exemplified by the magnitude 8.2 earthquake of 17 February 1996 that generated a local tsunami.

The 2010 swarm illustrates how short-lived clusters of events can punctuate the background seismicity driven by ongoing plate boundary interactions. Such sequences provide valuable data for refining local hazard assessments in eastern Indonesia.

References

USGS Earthquake Catalog
Global CMT Catalog
Indonesian Meteorological, Climatological, and Geophysical Agency (BMKG) reports