The 2007 Rengasdengklok Earthquake and Tectonic Setting of West Java

On 8 August 2007 at 17:05 local time, a magnitude 7.5 earthquake struck 35 km north-northeast of Rengasdengklok in West Java, Indonesia, at a depth of 280 km. The event occurred within the subducting slab of the Indo-Australian Plate beneath the Sunda Plate, producing deep intraslab seismicity rather than shallow crustal rupture. West Java sits above the Sunda subduction zone, where the Indo-Australian Plate converges northward at roughly 6–7 cm per year. This tectonic interaction generates both megathrust earthquakes at the plate interface and deeper events within the descending slab. At depths exceeding 200 km, mineral phase transitions and dehydration reactions can trigger brittle failure, consistent with the 280 km focal depth recorded for the 2007 event. The broader Indonesian archipelago forms part of the Pacific Ring of Fire, where multiple subduction systems produce frequent moderate-to-large earthquakes. Historical records document destructive events in Java dating back centuries, including the 1780 and 1852 shocks near Batavia (modern Jakarta) and the 2006 Yogyakarta earthquake farther east. Deep-focus earthquakes like the 2007 Rengasdengklok event are less likely to generate strong surface shaking but can still be felt across wide areas because of efficient wave propagation through the mantle. Seismic monitoring by regional networks has improved understanding of slab geometry beneath Java, revealing a steeply dipping Wadati-Benioff zone that extends to depths greater than 600 km. Continued subduction drives ongoing seismic hazard, with both interface and intraslab sources contributing to the regional risk profile.

References

USGS Earthquake Catalog (event parameters)
Global CMT Project (focal mechanism context)
Hamilton, W. (1979). Tectonics of the Indonesian Region. USGS Professional Paper.