The Previous Occurrence of Indian Ocean Tsunami- Geological Evidence from the Southeastern Coast of India
Abstract
The 2004 Indian Ocean tsunami is generally considered to be an event without any historical precedence. No known historical record exists on similar sized prior event of 2004 Indian Ocean tsunami magnitude. However, a closer look at the "Manimekhalai" an ancient Tamil literature from South India reveal references to a sea surge event around A.D. 1000 that may have affected the town of Pumbuhar (a ~2000 year old historical port town also known as Kaveripattinam), located at southeastern coast of India. The literary references, however, cannot be taken as historical facts unless geological evidence supports them. With this in mind, we had trenched some selected sites in the southeast Indian coastal village of Vanagiri located near Pumbuhar (Kaveripattinam). Our shallow trench sites placed roughly 1 km from present coastal margin exposed parallel laminated paleobeach facies at base of the trench overlain by relatively thick low-angle cross-bedded sand sheets sandwiched between clayey beds followed by thick soil horizon that forms the present day surface. The cross-bedded sand sheet units are bounded by fining upward transitional contact on top and an erosional contact at the bottom and is characterized by presence of heavy mineral lamination, rip-up clay clasts, contortions, occasional mud drapes and rare pottery shards. The sand sheet units are typically thick towards sea and pinches out landward forming a wedge-shaped body. The grain size and micro faunal analyses of sand sheets indicate bimodal grain size distribution and presence of foraminifera, respectively. Preliminary thermal luminescence ages obtained from the pottery shards preserved in units from below and above the sand sheets bracket age of the event between 1836+/-172 and 1017+/-168 ybp, which roughly corresponds to the age of sea surge referenced in "Manimekhalai". Further work is underway to understand geometry, fauna, lithology, age, sedimentary and chemistry of this candidate paleo tsunami deposits.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.T53E2013R
- Keywords:
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- 3040 Plate tectonics (8150;
- 8155;
- 8157;
- 8158);
- 4564 Tsunamis and storm surges;
- 7209 Earthquake dynamics (1242);
- 8107 Continental neotectonics (8002);
- 8170 Subduction zone processes (1031;
- 3060;
- 3613;
- 8413)