Characteristics of Tsunami and paleo Tsunami deposits in South Andaman Island, India

摘要

The 2004 26th December 2004, Tsunami deposits of were collected by pitting, trenching and coring from Tsunami affected areas like Collinpur and Wandoor of South Andaman during 2008 and 2010. Individual core and trench sediments were analysed in laboratory for sedimentology, mineralogy, micro paleontology and organic Carbon content. The 2004 tsunamigenic sediments were found to be black coloured humic mud-fine sand often mixed with shell fragments and/or Coral boulders. At Collinpur, from sedimentological and micro paleontological signatures, two Paleo Tsunami horizons are also identified between 107 to 126.4 cm and 47 to 71 cm depths. At Wandoor, only one Paleo Tsunami deposit can be identified between 35 and 65 cm depth. Each of these deposits consists of black coloured mud with fine sand and it resembles the 2004 Tsunami deposit. Presence of dominantly benthic foraminifera occasionally from depth more than 30 m found at a Paleo Tsunami horizon at Collinpur, indicates that the Tsunami entrained sediments from neritic bathymetry. Paleo Tsunami Horizons are correlated with the Tsunamis events of 1941 and 1881.