Influence of sedimentary layering on tsunami generation

TL;DR

This study investigates how sedimentary layers influence tsunami generation by modeling seabed displacements during underwater earthquakes, revealing that sediments can amplify deformations under certain conditions.

Contribution

It provides a quantitative analysis of sediment effects on seabed displacement during earthquakes, using finite element simulations to compare homogeneous and layered models.

Findings

Sediment layers can amplify seabed displacements.

Differences observed between homogeneous and layered models.

Numerical simulations reveal potential deformation amplification.

Abstract

The present article is devoted to the influence of sediment layers on the process of tsunami generation. The main scope here is to demonstrate and especially quantify the effect of sedimentation on vertical displacements of the seabed due to an underwater earthquake. The fault is modelled as a Volterra-type dislocation in an elastic half-space. The elastodynamics equations are integrated with a finite element method. A comparison between two cases is performed. The first one corresponds to the classical situation of an elastic homogeneous and isotropic half-space, which is traditionally used for the generation of tsunamis. The second test case takes into account the presence of a sediment layer separating the oceanic column from the hard rock. Some important differences are revealed. We conjecture that deformations in the generation region may be amplified by sedimentary deposits, at least for some parameter values. The mechanism of amplification is studied through careful numerical simulations.