Numerical modelling of generation, propagation and run-up of tsunamis caused by oceanic impacts: model strategy and technical solutions

Abstract

SUMMARY Hypervelocity impacts of asteroids in marine environments produce tsunami waves independent of the water depth and the diameter of the projectile. However, the characteristics of the induced waves are affected by these parameters. We present a model, consisting of the wellknown SALE impact model and a non-linear wave propagation model, to study the generation and subsequent spread out of the initial wave pattern caused by the strike of an asteroid or comet in the ocean. The numerical simulation of oceanic impacts requires some changes and extensions to the original SALE code. Especially, the handling of different materials (water and solid rocks) is crucial as they are involved in the cratering process. For the simulation of the propagation of tsunami waves that are generated by the impact process we use a newly developed wave propagation model, which is based on the non-linear shallow water theory with boundary conditions derived from the impact model. The run-up of the tsunami wave on the coastline is implemented as a special case of reflection and is realized by the wellestablished MOST code. Besides the model description we exemplify the capability of our modelling scheme by the simulation of the strike of an asteroid 800 m in diameter on a 5000-m-deep ocean at 10.2 km s −1 , the subsequent propagation of the induced tsunami waves over an artificial bathymetry and the run-up of the wave on the coast.