  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.
