Estimation of Absorbing Boundary Parameters for near Surface Seismic Modeling

Artificial boundaries are necessary in seismic numerical modeling to constrain the computational limits. Special treatment is necessary to reduce spurious reflections from these artificial boundaries. For near-surface seismic modeling, boundary processing is particularly important due to the presence of surface waves. The Perfectly Matched Layer (PML) method is an efficient way of attenuating boundary reflections of body waves and surface waves. This approach is widely used by modern seismic modeling programs. PML attenuation parameters are critical to the effectiveness of boundary absorbing. However, choosing the appropriate values for these parameters remains a challenge. In many cases, they are determined by experience or trial and error calculation. For a specific implementation of the PML absorbing method, the attenuation effectiveness varies with different sets of PML parameters. Through analysis on PML attenuation processes and numerical testing, we established an empirical relationship between the PML parameters and attenuation effectiveness, thereby providing a practical approach for determining the proper PML parameters for near-surface seismic modeling.