The 2016 M7.8 Earthquake Southwest of Sumatra

On 2 March 2016 at 12:49 local time, a magnitude 7.8 earthquake occurred southwest of Sumatra, Indonesia, at a focal depth of 24 km. The event is recorded as the sole strong earthquake (M 7.8) in the region since 1 January 2000. The epicentral area lies along the Sunda subduction zone, where the Indo-Australian Plate converges with and subducts beneath the Eurasian Plate at rates of approximately 5–6 cm per year. This tectonic boundary forms the Sunda Trench and generates frequent seismicity through megathrust and intraslab faulting. The 24 km depth places the hypocenter within the upper portion of the subducting slab, consistent with intermediate-depth events observed in this margin. The broader geological setting of Sumatra reflects long-term subduction-related processes, including arc volcanism, accretionary wedge development, and strike-slip faulting along the Great Sumatran Fault. These features contribute to the island’s elevated seismic hazard. The March 2016 earthquake exemplifies the ongoing release of strain accumulated along the plate interface.

References

USGS Earthquake Catalog Global CMT Catalog