Characterisation of Pre and Post-Tsunami Sediments by Grain Size Analysis Using G2Sd Package in R Programming from Nagoor to Poompuhar, Tamil Nadu, India

Abstract

India witnessed a massive tsunami on 26^th of December 2004, which adversely affected the East coast of India. This research focuses on the coastline between Nagoor to Poompuhar, Tamil Nadu which lies for a stretch of 35 km. Eight stations, namely, Poompuhar, Chinnangudi, Kuttyandiyur, Chandrapadi, Kottucherimedu, Karaikal Beach, Vadakku Vanjiyur North, and Nagoor Beach were chosen and a total of 73 samples were studied. The motive is to study the characteristics of pre and post tsunami sediment samples by analysing their grain size. The statistics of the sediments were done using G2Sd package of R programme, which showed lowering in the mean values of phi, percentage of increase in bimodality, change in skewness, and moderately well sorted sediments post tsunami indicating high-energy circumstances. The bivariate plots were plotted between different parameters to get more insight about depositional environments. Linear Discriminate Functions reveal the samples of pre-tsunami were deposited by aeolian process but most of the post-tsunami samples were deposited by beach process and 100% are from shallow marine conditions. The CM pattern and tractive current plots reveal the gradual suspension in pre tsunami whereas rolling in post tsunami. The characteristics of sediments of pre- and posttsunami in a more effective manner are presented in this paper.