Tsunami effects on shallow waters: From wave scattering to land inundation

Abstract

On 26 December 2004, one of the strongest Earthquake occurred in the Indian ocean of the Western coast of northern Sumatra, Indonesia. Measuring M w = 9.3 mega-thrust, this Earthquake triggered a massive tsunami that struck the Indian ocean neighboring countries and Somalia. The devastating evidence of the damage caused by this highly destructive waves has been recorded via in-situ measurements and by satellite imagery. Based on our previous work with SPOT-5 imagery [6], where we reported observed tsunami wave properties such as interference, reflection and refraction generated by the transoceanic propagation of the tsunami off the coast of Thailand; coupled with recent reports on the extend, duration, speed and size of the Sumatra earthquake, we report a study of the effects that these traveling waves had on areas of shallow waters. Wave properties inferred from SPOT-5 images and numerical modeling, are used to calculate wave run-up and water penetration and inundation levels of the nearby beaches. Near shore we use shallow-water theory to calculate the evolution and runup of the emerging non breaking waves by first deriving several sea-surface profiles for the leading wave of a tsunami. As a complementary step, runup and inundation model calculations are compared with independent results obtained from detailed damage assessment performed on pre- and post- tsunami images of the affected region.