M 7.1 - 119 km S of Isangel, Vanuatu

Tectonic Summary

The March 25, 2007, M 7.1 Vanuatu earthquake occurred as the result of shallow reverse faulting less than 100 km to the east of the South New Hebrides Trench, on or near the subduction zone plate boundary between the Australia and Pacific plates. At the location of the earthquake, the Australia plate subducts to the east-northeast with respect to the New Hebrides microplate (a segment of the much larger Pacific plate) at a velocity of about 79 mm/yr. The March 25th earthquake’s location, depth, and focal mechanism solutions are consistent with the earthquake resulting from northeastward-dipping thrust faulting associated with subduction along this plate boundary.

The Vanuatu region experiences a very high level of earthquake activity, and more than two dozen events of M 7 or larger have occurred within 300 km of the March 25, 2007, event since the beginning of the 20th century. Recent large earthquakes close to the March 25th event include a M 7.3 earthquake in December 2003, approximately 150 km to the south. In February 1990, a M 7.0 event had an almost identical location to this 2007 earthquake. Like the March 25th event, no damage or casualties were reported. The subducting Australia plate is seismically active to depths of about 350 km in this region.

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)