Numerical Simulation of Tsunami in Indian Ocean

Student: J. Appuhamy
Supervisors: Prof Stefano Tinti, Dr Carlo Lai

Abstract

The tsunami is the most formidable of all natural hazards. It is usually generated as a result of seismotectonic motions of the ocean bottom in the seismic source zone. Tsunami waves propagate far from the source and can cause damage even in regions where the earthquake was not manifested. The unexpectedness of tsunami is an additional risk factor.

The 26th of December 2004 was an unforgettable day for all Sri Lankans as well as for the whole world. On that fateful day, tsunami waves struck the Eastern and Southern coasts of Sri Lanka as well as parts of Northern and Western coasts sweeping people away, causing flooding and destruction of infrastructures. When the huge waves surged up the coasts of Sri Lanka, the devastation of a tsunami brought forth a surge of generosity the likes of which the world has rarely seen. The tsunami waves were caused by an earthquake, measuring 9.1 on the Richter scale that occurred in the sea near Sumatra, Indonesia. The other neighboring countries affected by this tsunami were Indonesia, India, Maldives, Somalia and Thailand. Since many Sri Lankans did not have any previous experience of this nature, the damage caused to their lives was unbelievable. Thousands of people were displaced and disappeared or killed within a very short time.

Often the only way to determine the potential run-ups and inundation from a local or distant tsunami is to use numerical modeling, since data from past tsunamis is usually insufficient. Models can be initialized with potential worst case scenarios for the tsunami sources or for the waves just offshore to determine corresponding worst case scenarios for run-up and inundation. Models can also be initialized with smaller sources to understand the severity of the hazard for the less extreme but more frequent events. This information is then the basis for creating tsunami evacuation maps and procedures.

It then might be possible to use such simulations to predict tsunami behaviour immediately after an earthquake is detected and the government or the responsible authorities can take the necessary actions to evacuate the innocent residents to the safe areas shown in evacuation maps which have been created by numerical simulations. Since Sri Lankan island is located far enough from the destructive tsunamigenic plate boundaries, accurate and well timing warning can make our people educate enough to self evacuate to those safer locations and save the nation in future disasters..

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