Bulletin of the Seismological Society of America; December 2005; v. 95; no. 6;
p. 2216-2231; DOI: 10.1785/0120050014
© 2005 Seismological Society of America
Simulation of an Irregular Free Surface with a Displacement Finite-Difference Scheme
J. A. Pérez-Ruiz1,
F. Luzón1 and
A. García-Jerez1
1 Department of Applied
Physics
Instituto Andaluz de Geofísica
University of
Almería
Cañada de San Urbano
s/n
04120-Almería
Spain
In this article, we present a method to simulate wave propagation in a
2D medium with an irregular free surface by using a finite-difference
method. The free-surface conditions are developed through an explicit scheme in
displacement. In our technique, a conventional grid is used to define the zone
where there is material and the zone where there is not material. In this method
a fictitious line of material above the free surface is used to compute the
displacement at the free surface. A classification of the points that shape the
fictitious line is presented. Then displacements in the internal points of the
material are computed together with the displacements at the points of the free
surface, and subsequently the displacement at the points of the fictitious line
are updated applying the boundary conditions by using an explicit
finite-difference scheme. We present some results of the application of this
technique by means of the simulation of the seismic response of a canyon and a
mountain using an explosive source and a vertical force, respectively. We
compared the results with the synthetics calculated by the indirect boundary
element method (IBEM). First, we tested the method simulating the
wave propagation at a half-space with a planar surface. The comparison with the
results of the IBEM gave us confidence to deal with other models with
topography features. These topographical models provided results that were in
very good agreement with the results obtained by the IBEM.
Copyright © 2009 by Seismological Society of America