Historic submergence and tsunami destruction of Nancowrie, Kamorta, Katchall and Trinket Islands of Nicobar district: Consequences of 26 December 2004 Sumatra-Andaman earthquake

The 26 December 2004 Sumatra-Andaman earthquake is one of the largest plate-boundary earthquakes in the recent seismic history of the world. This earthquake has also generated the greatest tsunami run-up and coastal devastation ever recorded. Our field study at four major islands of Nancowrie group of Nicobar District in Andaman and Nicobar archipelago has revealed that the islands are vertically subsided by 1.0-1.75 m with the submergence of coastal land area by thousands of square kilometers. It is also suggested based on our field observations that societal and socioeconomic rejuvenation of the islands will need resurvey of entire topography of the islands, coastal bathymetry mapping and identification of newly developed ecological regimes. We have also prepared maps of the coastal submergence for these islands using field observations and remote sensing in this paper. Based on the present field study and geodetic studies by other workers, differential tilting of the Andaman micro-plate is also inferred.