Poster of the Molucca Sea Earthquake of 21 January 2007 - Magnitude 7.5

Tectonic Summary

Eastern Indonesia, forming the southeastern extremity of the Southeast Asian lithospheric plate, crushed between the northward-moving Indo-Australian and the westward-moving Pacific plates, is certainly the most complex active tectonic zone on earth. The relative motion of Australia toward the interior of the Sunda plate, about 70 mm/yr, drives the motion of small plates that are situated between the Australia plate and the interior of the Sunda plate.

Frequent volcanic eruptions and frequent earthquake shocks testify to the active tectonic processes which are currently in progress in response to the continued movement of these major plates. The distribution of small ocean basins, continental fragments, remnants of ancient magmatic arcs and numerous subduction complexes which make up the Indonesian region indicate that the past history of the region was equally tectonically active.