M7.2 earthquake 50 km WNW of Port-Vila, Vanuatu

Several people injured, two bridges destroyed and buildings and roads damaged on Efate. Rockslides blocked access to the wharf at Port-Vila. A tsunami with wave heights of 40 cm (peak-to-trough) recorded at Port-Vila.

The January 2, 2002, M 7.2 Vanuatu earthquake occurred as the result of shallow oblique reverse faulting on or near the convergent boundary between the Australia plate and the New Hebrides microplate (a segment of the much larger Pacific plate). Focal mechanism solutions indicate that rupture occurred on either a steeply dipping reverse fault or a shallowly dipping thrust fault striking northwest-southeast. At the location of the earthquake, the Australia plate moves to the east-northeast relative to the Pacific plate at a velocity of about 84 mm/yr, subducting at the New Hebrides Trench to the west of the January 2nd event. The earthquake’s location and depth are consistent with the earthquake having occurred close to the interplate thrust that defines the Australia-Pacific plate boundary at depth, though the obliquity of the focal mechanism solution to the subduction direction indicates that the event likely occurred on an intraplate fault within the Australia slab. Slip on a fault aligned with either nodal plane of the focal mechanism solution is consistent with this intraplate setting. The subducting Australia plate is seismically active to depths of about 300 km beneath the islands.

The Vanuatu region experiences a very high level of earthquake activity, with half a dozen events of M 7 or larger within 200 km of the January 2nd earthquake during the preceding 40 years. Recent large earthquakes near the January 2nd event include a M 7.5 earthquake in November 1999 and a M 7.2 earthquake in July 1994.

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)