Observational analysis on the run-up height and inundation along the Andhra coast during December 26, 2004 Indian Ocean tsunami

Abstract

The 26 December 2004 earthquake with magnitude of 9.3 triggered one of the most destructive tsunamis in the Indian Ocean and caused widespread inundation and extensive damage in terms of life and property along the coasts of several Asian countries. In India, the Andaman and Nicobar group of Islands, the coastal states of Tamil Nadu, Andhra Pradesh and Kerala were severely affected. Post tsunami field surveys were conducted along the Andhra coast (central part of east coast of India) to assess the tsunami run-up heights and inundation. Estimation of tsunami run-up heights and inundation relative to the mean sea level were made based on the water marks on permanent structures and marks of debris on trees. Observations revealed that the Andhra coast was largely affected by the tsunami and in general the intensity of the tsunami along the Andhra coast decreased from south to north. Maximum run-up heights of 4.5 m were observed in the southern parts and minimum run-up heights of 2 m were observed in the northern parts of the Andhra coast. While, the distance of inundation varied from 60 to 900 m along the coast. The interdependency between the tsunami run-up height and inundation with the physical setup of the shoreline has been identified. Also local features such as dunes, vegetation and steepness of beaches played vital role in reducing the impact of tsunami. Dependency of tsunami parameters on Coastal Characteristic Index (CCI) was attempted for the first time for the Indian coast. Good correlation has been observed between run-up heights, inundation and CCI. The width of the continental shelf also played a crucial role in causing damage to the coast.