Impact of the 26-12-04 tsunami

Overview by country: Thailand

Topography: the northern part of the coast is rocky and there are no significant coastal plains; the southern part of the coast is more flat; the island of Phuket is hilly with the main flat areas on the eastern side;
Geology: the northern part of the coast is volcanic; the southern part of the coast has sandy/clayey alluvial sediments; Phuket island has limestone and volcanic rocks
Hydrogeology: the aquifer along the coast consists of unconsolidated beach sand (4-6 m. depth) with a clay confining unit.
Vulnerability: Intrusion of saline water during the tsunami flood is expected in permeable sediments and in the porous limestone or volcanic rocks; retreat of coastline will cause inland movement of salt water interface
Water Supply: surveys by the Department of Groundwater Resources provide estimates of 1050 shallow dug wells and 248 tube wells contaminated by sea water; reports from the Department of Health (DOH) confirm that well water in Phuket and Phang Nga Provinces are free of contaminants and that the vast majority of wells in the tsunami-hit areas have been restored to use.
Remark:new sinkholes have been reported mainly outside the inundated zone, which may be related to the effect of the earthquake or the tsunami

Geological map of Thailand
Ref.: Geological map of South and East Asia, sheet no. 3. 1:5,000,000,CGMW, 1990