Coastal Effects of the December 26th Tsunami on Ko Phra Thong, Thailand
Abstract
Ko Phra Thong, located off the west coast of Thailand, is a barrier island with 15.5 km of western facing coastline, fully exposed to the Indian Ocean. The island was impacted by the December 26, 2004 tsunami and was the focus of this post-tsunami study. A series of field surveys were conducted in March 2006, to determine local run-up values and inundation along the coast. Although, we had anticipated similar impact along much of the island's coast, we found that tsunami impact had significant variation along Ko Phra Tong's exposed shoreline. Some areas on the island were completely destroyed, while other areas along the coast had very little visible damage (with the exception of salt inundation that destroyed vegetation). Phra Thong has a variety of terrain ranging from small mountains to open grassy fields as well as tidal inlets with very dense mangrove forests. Our results show that Ko Phra Thong had a wide range of run-up at the coastline ranging from 7 to 20 m above sea level. Tsunami inundation reached up to 2 km inland and most of the mangrove forests were completely destroyed Other impacts documented during the survey include significant coastal erosion, major modification of tidal channels, and the formation of new lagoons. Although this range of run-up could not be seen in numerical models, a recent high resolution numerical modeling study conducted for this area suggests that this range of impact may have been caused by wave focusing from the nearshore bathymetry (Ioualalen et al., 2006). A study done by Kawata et al. (2005) conducted a few months after the tsunami's impact showed run-ups that closely match their model hindcast results. However, the Kawata et al. survey did not cover Ko Phra Thong. The bathymetry and its affects on the numerical model are presented and compared with the wave heights and inundation measurements from this study.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFM.U53A0036B
- Keywords:
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- 4564 Tsunamis and storm surges