Poster of the Java, Indonesia Earthquake of 08 August 2007 - Magnitude 7.5

Tectonic Summary

The earthquake of August 8, 2007, occurred at a depth of about 290 km within the lithosphere of the Australia plate, which is subducting beneath the Sunda plate. In this region, the Australia plate moves to the north with respect to the Sunda plate with a velocity of about 58 mm/yr. The Australia plate is thrust beneath the Sunda plate at the Java trench, south of the island of Java, and is subducted to progressively greater depths with distance north of the trench. The subducted lithosphere beneath and north of Java is seismically active to a depth of about 650 km.

Earthquakes that have focal-depths between 70 and 300 km are commonly termed intermediate-depth earthquakes, and earthquakes with focal-depths greater than 300 km are termed deep-focus earthquakes. Intermediate-depth and deep-focus earthquakes represent deformation within subducted plates, rather than deformation at plate boundaries. Intermediate-depth and deep-focus earthquakes typically cause less damage on the ground surface above their foci than is the case with similar magnitude shallow-focus earthquakes, but large intermediate-depth and deep-focus earthquakes may be felt at great distance from their epicenters.