Lowrank seismic wave extrapolation on a staggered grid |

To test the performance of the proposed methods with a rough velocity model, we use a two-layer model with high velocity and density contrasts. The model is defined on a grid, with and . Velocities of the upper and lower layers are and . The densities of upper and lower layers are and respectively. A point source of a Ricker-wavelet with dominant frequency of 20 Hz is located in the center of the model at a depth of .The maximum frequency ( ) is around . Following Song et al. (2013), we still use the CFL number to specify the stability and define dispersion factor as to indicate the sample points per wavelength, where is the minimum velocity of the model. For modeling with above parameters, and .

Figure 12 shows a wavefield snapshot generated by lowrank FD with a time interval equal to . At this time interval, the SGFD method becomes unstable.

lfd4snap2,lfd8snap2
Wavefield snapshot in a two-layer model with variable density and velocity using (a) 4th order SGLFD method and (b) 8th order SGLFD method.
Figure 12. |
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Lowrank seismic wave extrapolation on a staggered grid |

2014-06-02