Simulation of Tsunami Inundation in East Coast of Sri Lanka

Abstract

Present tectonic activities around the Andaman–Sumatran subduction zone gives an alarming signal of a possibility of occurring tsunamis in the Indian Ocean again and could bring devastation for rim countries in the Indian Ocean. Hence, proper understanding about possible tsunami inundation levels is a prerequisite for disaster prevention and management processes in tsunami prone areas such as low elevation coastal areas in the eastern coast of Sri Lanka. Therefore, as an initial step, present study was carried out to simulate tsunami propagation and inundation for Kallady city in the eastern coast of Sri Lanka to understand about vulnerable areas for future tsunamis. Kallady is a low lying, populated coastal city in eastern province of Sri Lanka. In this study, tsunami wave propagation and inundation in Kallady area under different scenarios namely, 2004 tsunami event and two hypothetical tsunamis with magnitudes of 9.5 and 10.5 respectively, where the epicenter of the earthquake of hypothetical two tsunamis was assumed to be similar to the 2004 tsunami event. Tsunami wave propagation and successive land area inundation were simulated using ELIMO and Nays2DFlood solvers of iRIC interface accordingly. Bathymetric and topography data were obtained from GEBCO, SRTM and recent field investigations in 2017. Initial sea surface elevations were simulated using Okada’s formula. ELIMO resolves well the wave propagation. However, Nays2D Flood determines inundation level significantly lower since it only employs water level record to model the inundation.