M 7.0 - 40 km S of Kimbe, Papua New Guinea

  • 2001-10-31 09:10:20 (UTC)
  • 5.912°S 150.196°E
  • 33.0 km depth

Tectonic Summary

The October 31, 2001, M 7.0 earthquake in the New Britain region of Papua New Guinea occurred as the result of shallow thrust faulting on or near the plate boundary between the Australia and Pacific plates. In this region, the Australia plate moves to the east-northeast with respect to the Pacific plate at a velocity of about 105 mm/yr. At the location of the earthquake, some researchers consider the edges of the Australia and Pacific plates to be divided into several microplates that together take up the overall convergence between the Australia and Pacific playtes, including the Solomon Sea and South Bismark microplates local to this event. In this context, the October 31st event occurred along the boundary between the Solomon Sea and South Bismarck microplates. The Solomon Sea microplate moves slightly faster and more northeasterly with respect to the Pacific plate (and South Bismark microplate) than does the Australia plate due to sea-floor spreading in the Woodlark Basin to the east-southeast of the October 31st earthquake, facilitating the classic subduction evident beneath New Britain and New Ireland. The October 31st earthquake’s location, depth, and focal mechanism solutions are consistent with the earthquake resulting from thrust faulting along the shallow subduction thrust plate boundary, which is seismically active to depths of about 600 km beneath the island.

The New Britain region experiences a high level of earthquake activity, with 22 events of M 7 or larger within 400 km of the October 31st event since 1961. One of these events, a M 7.2 earthquake in May 1985, roughly 100 km to the east of the October 31st earthquake, resulted in at least one fatality. The region also has a history of large earthquakes occurring close together in time. In November 2000, three earthquakes of M 7.8+ occurred over a 2-day period approximately 50-300 km to the northeast of the October 31st earthquake. The largest of these earthquakes, a M 8.0 event, resulted in at least one fatality and two 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)

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