Tsunamigenic incisions produced by the December 2004 earthquake along the coasts of Thailand, Indonesia and Sri Lanka

Field observations and satellite images indicate that tsunami waves exhibit specific patterns during flooding and recession forming characteristic incisions in the coastal landscape. To study these incisions we analyze high resolution remote sensing images of the coastline of Indonesia, Thailand and Sri Lanka impacted by the tsunami of December 26th, 2004. The analysis sheds light on the different mechanisms by which currents scour incisions during the flooding and receding phases of a tsunami. During flooding the high velocity flow indents the levees of existing tidal channels and bays, leaving short flood scours. The receding water then dissects the coastline with equally spaced return channels widening toward the coast.