M 7.5 - 35 km NNE of Rengasdengklok, Indonesia

Tectonic Summary

The August 8, 2007, M 7.5 Java earthquake occurred as the result of oblique reverse faulting at an intermediate depth, approximately 280 km beneath the north coast of Java within the lithosphere of the Australia plate subducting beneath the Sunda plate. Focal mechanism solutions indicate that rupture occurred on either a steeply dipping east-striking reverse fault or a shallowly dipping, northwest-striking thrust fault. Of these two possible fault orientations, finite-fault modeling of globally recorded seismic data is more consistent with slip on the steep, east-striking fault. At the location of the earthquake, the Australia plate moves to the north with respect to the Sunda plate at a velocity of about 58 mm/yr. The Australia plate is thrust beneath the Sunda plate at the Sunda-Java Trench, south of the island of Java and the August 8th earthquake, 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 such as this one, with focal depths between 70 and 300 km, are commonly termed “intermediate-depth” earthquakes. Intermediate-depth earthquakes represent deformation within subducted slabs rather than at the shallow plate interface between subducting and overriding tectonic plates. They 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 earthquakes may be felt at great distance from their epicenters.

The most recent large earthquake local to this event was a M 7.7 earthquake in July 2006, very close to the Sunda-Java Trench. That event resulted in several hundred fatalities and widespread damage.

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)