Poster of the Papua, Indonesia Earthquake of 29 September 2010 - Magnitude 7.2

Tectonic Summary

The Papua, Indonesia region earthquake of September 29, 2010 occurred as a result of normal faulting along a section of the broad plate boundary system in eastern Indonesia to the northwest of the Aru Islands.

Eastern Indonesia is characterized by complex tectonics in which motions of numerous small microplates are accommodating the large-scale convergence between the Australia, Sunda and Pacific plates. The September 29 earthquake lies near the boundary between the proposed Banda Sea microplate and the Australia plate proper, which is oriented approximately north-northeast and accommodates divergent motion between these plates. The focal mechanism of the earthquake is consistent with its occurrence on such a boundary, though due to the complexity of tectonics in this region any specific association with a causative fault structure must be regarded as speculative, pending further study. At a broad scale, the Australia plate moves northwards with respect to the Sunda plate at a velocity of approximately 77 mm/yr in the region of the earthquake. In more detail, it has been estimated that the Banda Sea microplate moves westward with respect to the Australia plate with a velocity of about 15 mm/yr.

Todays earthquake was preceded approximately 27s earlier by a smaller, magnitude 6.2 event, from nearly the same epicenter. Eastern Indonesia is a tectonically active area with frequent moderate and large earthquakes. The region within 300 km of the September 29 event experienced over 30 earthquakes larger than M6 in the past half century.

Earthquake Report

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