Near Source Energy Partitioning for Regional Waves in 2D and 3D Models

摘要

The complex excitation and energy partitioning mechanisms yielding regional phases are difficult to empirically separate by data analysis. Thus, numerical modeling approaches are valuable for investigating excitation and propagation of regional seismic phases. We use accurate full-wave simulations (2D and 3D finite-difference method, and 2D boundary element method) to calculate seismic wave excitation and propagation in near-source region. An embedded array slowness analysis is used for quantifying how energy will be partitioned into the long-range propagation regime. Due to its high efficiency, the method can simulate near-source processes using very fine structures. A large number of source and model parameters can be examined for broad frequency ranges. We use this method to investigate the effect of volumetric and topographic scattering on the near-source energy partitioning for an explosion source. Different random velocity fluctuations and topographic models, variable source depth, and different Q models are investigated using numerical simulations. The responses of different phases as functions of frequency and source/model parameters are calculated and their energy budget evaluated.