Environmental and Geological Impacts of the 26 December 2004 Tsunami in Coastal Zone of Thailand – Overview of Short and Long-term Effects

Our paper presents selected short- and long-term environmental and geological impacts of the 26 December 2004 tsunami on the Andaman Sea coast of Thailand. The tsunami inundated the coastal zone more than 1.5 km inland and above 10 m a.s.l., causing coastal erosion mainly in the nearshore zone, beaches, river mouths and peninsulas. The tsunami runup was significantly influenced by nearshore bathymetry. Almost the entire inundation zone was covered with up to 0.5 m tsunami-laid sand and silty sand layer burying former soil. The layer has not eroded during subsequent rainy seasons and probably will be preserved in the geological record. The inland waters were salinated and the tsunami deposits were enriched in salts and bioavailable heavy metals and arsenic. Most of them were mobilized during rainy season. Sandy beaches -- the most tsunami damaged coastal habitat, recovered quickly after the tsunami event. Also, most of the land vegetation recovered within one year after the tsunami.