M 7.3 - 33 km NW of Port-Vila, Vanuatu

Tectonic Summary

The August 10, 2010, M 7.3 Vanuatu earthquake occurred as the result of shallow reverse faulting on or near the plate boundary between the Australia and Pacific plates in the Coral Sea region of the southwest Pacific. In the region of the earthquake, the Australia plate moves to the east-northeast relative to the Pacific plate at a velocity of about 85 mm/yr. The Australia plate thrusts underneath the Pacific plate at the Vanuatu Trench and dips to the east-northeast. The location, depth, focal mechanism solutions, and finite-fault modeling of globally distributed seismic data for the August 10th event are consistent with the earthquake resulting from reverse faulting associated with subduction along the Australia-Pacific plate boundary.

This earthquake was located approximately 500 km to the south of a sequence of large subduction thrust earthquakes that occurred in October of 2009. On October 7, 2009, two earthquakes of M 7.7 and M 7.8 occurred 15 minutes apart. After these events, a M 7.4 aftershock struck approximately 1 hour later, and two aftershocks (M 6.6 and M 6.8) occurred on the following day. On May 27, 2010, a M 7.1 earthquake occurred 100 km farther to the north of the October 2009 sequence. More broadly, the Vanuatu region experiences a very high level of earthquake activity, with almost 50 events of M 7 or larger recorded since 1973.

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)