Evaluation of Tsunami Risk Posed to Sri Lanka by Potential Mega-Thrust Earthquakes in the Makran Subduction Zone

This paper is concerned with a numerical study carried out to assess the threat posed to Sri Lanka by potential tsunamigenic earthquakes in the Makran subduction zone in the Arabian Sea off the south coasts of Pakistan and Iran. The fault plane model adopted in the present simulations corresponds to a worst-case scenario of simultaneous rupture of the entire eastern segment of the Makran Trench. A hydrodynamic model based on linear shallow-water equations was employed to simulate tsunami propagation from the source to the shoreline around Sri Lanka. The numerical simulations suggest that the maximum nearshore tsunami amplitudes along the coastal belts of the Western, North-Western and Southern Provinces are of the order of 1 m; the corresponding values for the Eastern and Northern provinces are even smaller, about 0.2 m and 0.1 m, respectively. The model results also indicate that the tsunami waves will first hit the coastal belt of the Western Province about 280 minutes after the earthquake, followed by Southern and North-Western Provinces. The results presented in this paper would be useful for authorities responsible for evacuation to make a better judgement as to the level of threat in different areas along the coastline, and to act accordingly, if a large earthquake were to occur in the Makran subduction zone.