Three-dimensional runup simulation of the 2004 Indian Ocean tsunami at the Lhok Nga twin peaks

Abstract

A post-tsunami runup survey for the 2004 Sumatra-Andaman earthquake showed that the highest runup which was recorded at Lhok Nga (West Banda Aceh, Sumatra). A reported maximum tsunami height of 35 m and maximum runup height of up to 51 m occurred near the Lhok Nga Twin Peaks (Labuhan and Ritieng). A numerical simulation was performed to reproduce tsunami characteristics in this area. The tsunami source was computed using fault parameters proposed by Tanioka et al. Tsunami wave propagation from the source to the coast was studied with 3D shallow-water equations. The coastal runup behavior of the tsunami at the Lhok Nga Twin Peaks was studied within a framework of fully nonlinear dispersive Reynolds-averaged Navier Stokes equations using the FLOW3D code. This approach made it possible to reproduce the extreme characteristics of the tsunami in this coastal area, including observed overflow through a saddleback between the twin peaks. The numerical simulation results compare well with data from field surveys.