M 7.0 - 121 km SSE of Biak, Indonesia

Tectonic Summary

The June 16, 2010, 03:16 UTC, M 7.0 earthquake near the north coast of Papua, Indonesia, occurred as a result of shallow strike-slip faulting. The causative fault has not yet been identified, though the radiation pattern of seismic waves generated by the earthquake is consistent with either left-lateral faulting on an east-northeast-striking fault or right-lateral faulting on a north-northwest-striking fault.

Eastern Indonesia is characterized by complex tectonics in which motions of numerous small plates are accommodating large-scale convergence among the Australia, Sunda, Pacific, and Philippine Sea plates. The June 16th earthquake lies near the boundary between what some workers term the Birds Head microplate and the Maoke microplate. This boundary has been modeled as accommodating approximately 80 mm/yr of left-lateral motion along an east-northeast trend. The focal mechanism solution of this earthquake is consistent with it occurring within the proposed microplate boundary, either as left-lateral slip on a boundary-parallel fault or as right-lateral slip on a conjugate fault that is tectonically related to the microplate boundary. In light of large uncertainty in tectonic modeling of eastern Indonesia, however, any particular hypothesis for the causative fault of the earthquake must be regarded as tentative pending further study.

Eastern Indonesia experiences many strong earthquakes. Since 1979, the region within 300 km of the mainshock of June 16, 2010, has experienced eight other earthquakes with magnitudes larger than 7, the largest of which was a M 8.2 event in February 1996 about 100 km to the north of the June 16th earthquake. The February 1996 event resulted in at least 166 fatalities and 423 injuries.

Hayes et al. (2016) Tectonic summaries of magnitude 7 and greater earthquakes from 2000 to 2015, USGS Open-File Report 2016-1192. (5.2 MB PDF)