Tsunami wave propagation in the Arabian Sea and its implications on run-up/inundation characteristics along the Kerala coast

Abstract

December 2004 tsunami generated by the M9.3 Sumatra-Andaman earthquake devastated many parts of the Kerala coast of southwest India, though it was in the shadow zone of that tsunami. Post-tsunami field survey and sea level data provided a rare opportunity for the study of wave transformation characteristics along this coast. A review of the available studies on the effects of 2004 tsunami wave propagation like the observed focusing/defocusing, number and arrival times of waves along the Kerala coast is undertaken in this paper. The important processes identified to be responsible for the observed run-up and inundation are refraction, diffraction, reflection, and total internal reflection. Water level variations from the third day onwards are attributed to energy trapping on the continental shelf and secondary undulations. In addition, the implications of the wave propagation characteristics on tsunami run-up and inundation along the Kerala coast for the two probable sources of tsunami viz. Sumatra and Makran are examined through numerical modeling. It is found that the central and northern sectors of the coast are more hazard prone to the Makran than Sumatra for the same rupture intensity.