I am using staggered grid FDTD for solving elastic wave equation. A description of which can be found at (geodynamics.usc.edu/~becker/teaching/557/reading/Virieux1987.pdf). I have generated a synthetic seismogram (description below) using it.
Synthetic seismogram : To generate a synthetic seismogram, a source is placed at top and an array of receiver is laid along the surface. A synthetic seismogram can be visualize as in this youtube animation (www.youtube.com/watch?v=_Gjr5EWNIQk)
My Problem is the spurious oscillations generated in FDTD simulation for elastic wave. I have taken care of grid dispersion which requires 10 grid points per wavelength (minimum). still I feel there is a lot of dispersion in it. The model I have taken is a homogeneous elastic model with absorbing (damp) type boundary conditions along all the edges.
Vp = 2000 m/s; Vs = 1500 m/s;
Grid spacing: dx = dv = 5m;
time sampling: dt = 1msec
Source: Ricker (20Hz).
Following is the response of at one receiver (k/a trace) and a snap of wave
Presently I don't have privileged to add more than two link so I edited and joined two pics of traces for soft and hard types of sources.
The corrected trace after applying pressure source (soft type) is shown now. But still there are wriggles trailing the wave