Tectonic Summary

The April 11, 2014, M 7.1 earthquake southwest of Panguna, Papua New Guinea, occurred as the result of shallow thrust faulting on or near the subduction zone interface between the subducting Australia plate and overriding Pacific plate. At the location of the earthquake, the Australia plate moves towards the east-northeast at a rate of 102 mm/yr with respect to the Pacific plate, and begins its subduction into the mantle beneath Bougainville Island at the New Britain Trench south of the earthquake. The moment tensor and depth of the earthquake are consistent with thrust-type motion on the interface between these two plates. Note that at the location of the earthquake, some researchers consider the edge of the Australia plate to be divided into several microplates that take up the overall convergence between the Australia and Pacific plates. Here, the Solomon Sea microplate moves slightly faster and more northeasterly relative to the Pacific plate than does the Australia plate due to sea-floor spreading in the Woodlark Basin several hundred kilometers to the south of the April 11th earthquake.

In the Papua New Guinea region, the boundary between the Australia and Pacific plates is very active seismically; 35 M 7+ events have occurred within 250 km of the April 11, 2014, earthquake over the past century. None are known to have caused any shaking-related fatalities. The largest was a M 8.0 event 175 km to the northwest of the April 11, 2014, earthquake, and was one of two M 8+ earthquakes 140 km apart in July 1971. The M 8.1 Solomon Islands earthquake in April 2007, which caused a devastating tsunami, was 300 km southeast of the April 11, 2014, event.

A M 6.5 aftershock occurred at 08:16 UTC approximately 25 km to the southeast of the M 7.1 mainshock. Like the mainshock, the moment tensor and depth of the aftershock are consistent with thrust faulting on the Australia-Pacific plate boundary interface.

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)

Event Details

Event Map

Tectonic Summary

Tectonic Summary

Historical Magnitude 4.5+ (100km)