TSUNAMI COMPUTATION ALONG NORTH SUMATRA AND PENANG ISLAND DUE TO A TIME DEPENDENT SOURCE ASSOCIATED WITH THE INDONESIAN TSUNAMI 2004 USING A POLAR COORDINATE SHALLOW WATER MODEL

Md. Fazlul Karim (Malaysia), G. D. Roy (Bangladesh), Ahmad Izani M. Ismail (Malaysia) and Mohammed Ashaque Meah (Malaysia)

Received January 21, 2008

Abstract

In an earlier study [15], a nonlinear polar coordinate shallow water model was developed to compute different aspects of tsunami along North Sumatra in Indonesia and Penang Island in Peninsular Malaysia, associated with the Indonesian tsunami 2004. In that study, the initial tsunami wave was generated instantaneously in the source zone along the fault line and that was used as the initial condition of the model. But in reality, starting from the epicenter the rupture along the fault line occurred gradually northward with a rupture front speed 2-3 km/s and whole process was completed in 500-600s [10]. Thus, the initial disturbance of the sea surface along the source zone is also time dependent. In this study, the model of Roy et al. [15], has been used to simulate different aspects of the tsunami associated with Indonesian tsunami 2004, using a time dependent source. The computed results due to the time dependent source agree well with those of observations. A comparison between the responses due to time dependent source and its corresponding instantaneous version has also been carried out in order to test the efficiency of the instant source. The comparison shows that the responses due to the time dependent source have significant differences with those due to instantaneous version.

Keywords and phrases: time dependent source, tsunami surge, tsunami propagation, Sumatra and Penang Islands, shallow water model, cylindrical polar coordinates.