Inundation studies for Nagapattinam region on the east coast of India due to tsunamigenic earthquakes from the Andaman region

摘要

The Andaman-Sumatra arc is an active subduction zone and had generated several destructive tsunamis in the past. The 2004 Indian Ocean tsunami has led to more and more paleotsunamic research of identifying geological evidences of past submergence. These paleotsunamic studies along the east coast of India are suggestive of a predecessor for the 2004 tsunami about 1,000 years back. One of the historical earthquakes in this region was the earthquake of June 26, 1941 in the North Andaman region which was one of the strongest in Bay of Bengal. This earthquake had triggered a tsunami which affected the east coast of India. After few hours of the occurrence of this earthquake, a series of strong aftershocks occurred in the same source region. Two events with magnitude 6.0 struck within 24 h after the main shock of June 27, 1941, and there were 14 aftershocks of magnitude up to 6.0 till January 1942. In this paper, we have modeled two scenarios of tsunamigenic earthquakes, i.e., the 1941 North Andaman earthquake and another possibly great tsunamigenic earthquake. The run-ups at Nagapattinam due to the 1941 earthquake is around 0.95-1.25 m and inundation extent ranges from 77 to 110 m, and for a possibly large tsunamigenic earthquake, we find the run-ups are around 2.39-3.60 m and inundation extent ranges from 462 to 638 m.