SEMINAR - Po Chen

A Unified Approach to Full-3D Waveform Tomography and Seismic Source Inversion

Po Chen
Lamont-Doherty Earth Observatory
Columbia University

Seismic hazard analysis depends upon seismology to quantify both the seismic sources that generate seismic waves and the Earth structure through which seismic waves propagate. In this talk, I will present a unified approach for iteratively improving the 3D Earth structure model and seismic source models by solving the elastic/anelastic seismic wave equation using purely numerical methods such as finite-difference. First, I will start with an introduction to the background and motivation, which is primarily focused on ground-motion quantification and prediction. Second, I’ll explain how we can quantify the misfit between model-predicted waveforms and the observed waveforms using time- and frequency-dependent phase-delay and amplitude anomalies and how we can use them to evaluate the quality of a given structural or source model. Third, I will introduce the concept of receiver Green tensor (RGT) and its central role in constructing the partial derivatives needed for near-real-time seismic source parameter inversions and the Fréchet kernels for full-3D waveform tomography. Fourth, I’ll present the results that we have obtained from applying this unified approach to the Los Angeles region. Last, I’ll end my talk with a short discussion of some on-going research and a summary.