(Woods Hole Oceanographic Institution, 1989-10)
Allen, Julie M.; Burns, D. R.
A three dimensional, second order finite difference method was used to create synthetic
seismograms for elastic wave propagation in heterogeneous media. These synthetic seismograms are
used to model rough seafloor, the shallow crust, or complex structural and stratigraphic settings with
strong lateral heterogeneities. The finite difference method is preferred because it allows models of
any complexity to be generated and includes all multiple scattering, wave conversion and diffraction
effects. The method uses a fully staggered grid as developed by Virieux (1986). Wavefront snapshots
and time series output allow the scattering and focussing of different wave modes with direction to
be visualized.
The extensive calculations required for realistic size models stretches the resources of serial
computers like the VAX 8800. On the Connection Machine, a massively parallel computer, the
finite difference grid can be directly mapped onto the virtual processors, reducing the nested time
and space loops in the serial code to a single time loop. As a result, the computation time is reduced
dramatically.
