Seismicity and seismotectonics in and around Sri Lanka: a synoptic review

Abstract

Seismicity and seismotectonics in and around Sri Lanka are reviewed, considering the country in both the local and regional contexts. Seismic activity reported within the country indicates a close correlation with the local geotectonic setup that comprises certain active features such as lineaments and faults, bedrock fractures, thrust/shear zones and tectonic movements of individual mini-plates. Seismicity in the regional context is discussed, evaluating identified active zones in the northern Indian Ocean surrounding the country. A large area of diffuse seismicity located south-southeast of Sri Lanka enclosing the northern part of the Ninetyeast Ridge, could be a dominant source of strong shallow intraplate earthquakes, and could render direct threats of striking large-magnitude events in close proximity to the country. The oceanic region west of Sri Lanka and continental region of southern peninsular India are not as active, more like dormant areas with sparse seismicity. However, seismogenic potential of these regions may not be completely ruled out, given evidence of previous isolated strong events.