Propagation of the Sumatra Tsunami in the Southeast Arabian Sea and Inundation along the Lakshadweep and Kerala Coast of India

Abstract

A study of the propagation of the 2004 tsunami in the South East Arabian Sea (SEAS) and the tsunami induced run-up and inundation along the Kerala and Lakshadweep coasts were taken up using posttsunami field survey data and numerical modeling. The role of different wave transformation processes like diffraction, refraction, reflection, and total internal reflection in bringing out the observed run-up and inundation characteristics along the Kerala and Lakshadweep coasts are discussed. Simulations using the TUNAMI N2 model were carried out for three different sources viz. Sumatra 2004, Makran 1945 and a hypothetical potentially worst case from Makran. The results of tsunami vulnerability analysis in terms of run-up and inundation for the entire Kerala coast and four selected Islands of Lakshadweep viz. Androth, Chetlat, Kadmat and Kavaratti show strikingly different run-up and inundation characteristics. While the Kerala coast appears to be vulnerable for inundation due to tsunami from different sources, the Lakshadweep coasts do not appear to be vulnerable. The modeling results for Sea Level Rise scenario for selected sectors indicate that sea level rise can definitely make many fold increase in inundation in some of the stretches. For planning mitigation measures, it would be highly essential to carry out numerical simulations for the extreme SLR scenarios for the whole coast by providing high resolution topographic grid for the coastal zone.