Rotated Staggered Grid Finite Difference Modeling in the Presence of Underground Cavities

摘要

We combined the improved vacuum formulation and the rotated staggered grid finite difference method to implement the high order rotated staggered finite difference elastic wave-field simulation at the presence of underground cavities.Our method overcomes the defect of rotated staggered finite difference when modeling the free surface condition which is only stable at second order spatial FD operators,through the comparison with existing vacuum formulation testifies our methods accuracy and stability.The perfectly Matched Layer (PML) absorbing boundary condition is applied to decrease the reflection from the edges of the numerical model.Different seismograms are calculated with models without voids and models contain voids with different size and depth under different source wavelet frequency.The effects of different cavity size and depth and the source wavelet frequency are evaluated from the snapshots and seismograms with and without the cavity.