POSSIBLE TSUNAMI ALONG THE SOUTHERN COASTS OF IRAN BORDERING THE INDIAN OCEAN

The catastrophic tsunami that struck southern Asia on December 26, 2004, emphasized the extraordinary social and economic damage that such an event can bring. The essential lesson to be learned from this event is that the risk of tsunami is real for the Indian Ocean basin and appropriate measures should be taken for the vulnerable coastlines. One of the most tsunamigenic sources in the Indian Ocean is Makran Subduction Zone (MSZ) offshore of Iran, Pakistan, India and Oman. In this zone the Oman oceanic lithosphere slips below the Iranian micro-plate at the estimated rate of 19 mm/yr. Historically, the MSZ has generated some tsunamigenic earthquakes like that of 28 November 1945 which took the lives of more than 4000 people along the coasts of Iran, Pakistan, India, and Oman. Considering these facts, in this study the tsunami hazard associated with the MSZ is investigated. Today, we know that the pattern and extent of vertical ground deformation from an earthquake determines whether or not a tsunami is formed. Therefore, in this paper a computer program is developed based on Mansinha and Smylie (1971) formula to predict the seafloor deformation due to the earthquake occurrence in the subduction zone. Considering realistic parameters for MSZ and ruptured area and using the developed computer program, the seafloor deformation is calculated for several earthquake scenarios with moment magnitudes ranging between 6.5 and 8.5. The results obtained here show that the risk of tsunami generation from MSZ can be classified into three main categories, as follows: (1) very little risk for tsunami generation in the case of occurrence of an earthquake having magnitude up to 7; (2) little to medium risk (Magnitude ranging 7 to 7.5); and (3) high risk (Magnitude greater than 7.5).