Tidal Wave Catastrophe For The First Time In India: Should We Live Under Its Threat Forever?
Dr. Mu. Ramkumar, Department of Geology, Periyar University, Salem (About the Author)
December 28, 2004

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Fig.1 showing major plate boundaries of the world
Source: United States Geological Survey
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Fig.2 showing major plate boundaries of the world
Source: United States Geological Survey
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There has been widespread panic all over the coastal districts of Tamil Nadu and Andhra Pradesh besides coastal regions of Srilanka owing to the occurrence of major earthquake measuring 8.5 richter scale at 260km southwest of Ausi Island of Indonesia, which is also recorded at 7.3 richter scale in Bengal, followed by tsunami waves that inundated southern India, Srilanka, Malaysia and Indonesia. Magnitudewise, this earthquake is one of the major earthquakes recorded in recent history and its epicenter might have been emanated from deep-seated faultlines possibly near crust-mantle interface.

As shown in the figure 1, the earth's surface is made up of seven large and many small moving plates, that float over semi-liquid molten rock mass, just like ice cubes float over water. These plates either move away from each other or against each other or along each other’s boundary. All along the boundaries of these plates, depending on their relative movement with reference to other plates, either mountain chains or ocean basins form or at many a locality (Figure 2), major volcanoes and hotspots form. 

Earthquake hazard prone areas are located all along these plate boundaries. During the past 25 years, earthquakes have caused more than 1 million deaths worldwide. Seventy percent of the earthquakes measuring seven or over on the Richter scale occurred in the Asian and Pacific region, at an average rate of 15 per year. The most devastating earthquake in the world in recent history, the Tangshan earthquake, which occurred in China on 28 July 1976, is reported to have claimed over 240,000 lives. The region in and around Japan and Indonasia, Java and Sumadra Island is one such seismicity prone area (Figure 2) that constantly experiences minor to major earthquakes.

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About the Author