Physical-based Real-time Ground Motion Prediction and its Application in Earthquake Source Studies

Efficient and physics-based ground motion simulations are necessary for source parameter estimation and seismic hazard assessment after large earthquakes. Damages to engineering structures by an earthquake depend on the entire time history of the ground motion, which is affected by a number of factors including the source rupture process, three-dimensional (3D) velocity structure, surface topography, and local site condition. Among these four factors, the source process may be most important because it not only leads to directivity effect, a major factor in determining the spatial pattern of the ground motion, but also has influence on how the other three factors affect the ground motion. We develop an efficient and physics-based approach to the calculation of earthquake-induced ground motions in which all the above four factors are properly accounted for. In this approach, realistic ground motion time series are obtained from a pre-calculated seismic Green tensor database. The rapid ground motion prediction enables us conduct in realistic 3D Earth models routine source studies such as determining the moment tensor solutions and resolving the fault plane ambiguity. It even permits near real-time slip history inversions using regional waveforms. We will use several moderate earthquakes as examples to demonstrate the concept and performance of our approach.