Tsunamis Generated by Submarine Landslides

Abstract

Submarine landslides can generate tsunamis and cause coastal hazard. Because the horizontal scale of submarine landslide is comparable to water depth and much smaller than the scale of earthquake fault area, the tsunami characteristics is very different from earthquake-generated tsunami which is usually approximated as a shallow-water wave. Several approaches have been proposed to model the tsunami generation by submarine landslides, and they can be grouped into: landslide as fluid motion, rigid-body motion, and initial or kinematic water surface profiles. Two examples of tsunamis from submarine landslides are described. The first one is the 1998 Papua New Guinea tsunami. While the tsunami records at far-field, around Japan, were basically reproduced by earthquake fault motion, locally large tsunami heights around Sissano Lagoon needed additional source such as submarine slumping. The 1741 Oshima-oshima tsunami in Japan Sea was modeled by a submarine landslide associated with sector collapse of the volcano. While the subaerial landslide size and volume were not enough to produce the tsunami that caused damage as far as Korean coast, tsunami simulation from the recently mapped submarine landslide could reproduce the observed tsunami heights.