The 2009 M7.5 Earthquake 266 km North of Bamboo Flat, India
On August 10, 2009, at 19:55 UTC, a magnitude 7.5 earthquake struck 266 km north of Bamboo Flat in India's Andaman Islands. The event occurred at a depth of 24.0 km. This earthquake represents one of the notable seismic events in the region since 2000.
The Andaman Islands lie along the convergent boundary where the Indian Plate subducts beneath the Burma Plate. This tectonic setting produces frequent earthquakes as accumulated strain is released along the plate interface and associated faults. The islands form part of an accretionary wedge above the subduction zone, with the trench located to the west. Historical records document major seismic activity in the area, including the devastating 2004 Mw 9.1–9.3 Sumatra-Andaman earthquake that ruptured a vast segment of the same subduction zone.
The 2009 event occurred within this active tectonic framework. Its moderate depth placed it in the upper portion of the subducting slab or overlying crust, consistent with typical seismicity patterns observed in the Andaman segment. Ground shaking was felt across parts of the Andaman and Nicobar Islands, though detailed damage reports remain limited due to the offshore location and relatively sparse population density in the immediate vicinity.
Geological studies of the region highlight ongoing deformation driven by oblique convergence between the plates. The subduction zone exhibits both thrust and strike-slip faulting, with the latter accommodating the lateral component of plate motion. Post-2004 aftershock sequences and subsequent independent events, such as the 2009 earthquake, illustrate the continued seismic hazard in this part of the Indian Ocean.
Updated assessments from global seismic networks confirm the parameters of the 2009 mainshock and underscore the persistent activity along the Burma Plate margin. Monitoring efforts continue to refine understanding of rupture processes and potential future events in this tectonically dynamic area.
References
USGS Earthquake Catalog Global CMT Project Indian Meteorological Department Seismological Reports