Poster of the Papua New Guinea Earthquake of 07 July 2013 - Magnitude 7.3

Tectonic Summary

The M 7.3 July 7 2013 earthquake northeast of Papua New Guinea occurred as a result of normal faulting approximately 380 km deep within the subducted Australia Plate. 200 km to the south of this event, the Australia Plate subducts beneath the Pacific plate at the New Britain Trench, moving towards the north-northeast at a rate of 103 mm/yr. The depth and faulting mechanism of the July 7 earthquake are consistent with the event resulting from internal (intraplate) deformation of the subducted slab, rather than as an interplate event on the shallow plate boundary interface. Crustal tectonics of the New Britain region are commonly described in terms of relative-motions of microplates that are situated at the boundary of the Australia and Pacific plates. The New Britain Trench region is familiar with large earthquakes; this subduction zone is one of the most seismically active regions of the world. Deep earthquakes (>300 km) are reasonably common as well; several M>6.5 earthquakes have occurred within 250 km of the July 7 event over the past 40 years, including a M 6.8 event in an almost identical location in June 1995. Because of their great depths, none are known to have caused damage. Intermediate-depth (70-300 km) and deep-focus (depth > 300 km) earthquakes are distinguished from shallow earthquakes (0-70 km) by the nature of their tectonic setting, and are in general less hazardous than their shallow counterparts, though they may be felt at great distances from their epicenters. The Australia slab in the region of the July 7 2013 earthquake is seismically active to depths of over 400 km.

Earthquake Report

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