Monte Carlo Simulations of Multiple Scattered Body and Rayleigh Waves in Elastic Media

Session: Environmental and Near Surface Seismology: From Glaciers and Rivers to Engineered Structures and Beyond [Poster]
Type: Poster
Date: 4/29/2020
Time: 08:00 AM
Room: Ballroom
Description: 

Time-lapse seismic monitoring exploits the sensitivity of coda waves to small changes in the subsurface and images the temporal and spatial evolution of seismic properties (e.g. density). This imaging method is complicated because the coda waves include multiply-scattered body and surface waves. The complication arises because these two types of waves possess different spatial sensitivities and can interact with each other via scattering. As a consequence of the latter, the energy ratio between the two types of waves evolves with time in the coda. Thus the estimation of this energy ratio is critical to obtain accurate monitoring results. The spatio-temporal evolution of energy partitioning in elastic media is not yet fully understood. In practice, one has to fix the energy ratio or even ignore the contributions of either surface or body waves. Based on scattering theory, we propose a Monte Carlo method to predict the energy partitioning between multiply-scattered body and Rayleigh waves as a function of time and depth in an elastic half-space. In the simulations, we use the single scattering conversion rates from body to Rayleigh waves (and vice-versa), which rely on the depth-dependent eigenfunctions of the Rayleigh waves. This research is a first step towards a complete modeling of coupled body- and Rayleigh-wave multiple scattering in elastic media.

Presenting Author: Zongbo Xu

Authors