PROGRESS IN THREE-DIMENSIONAL SIMULATIONS OF EXPLOSIONS AND EARTHQUAKES

Abstract : Advances in numerical methods for modeling seismic wave excitation and propagation and ever more powerful parallel computers are making it easier to simulate ground motions on the scale lengths (domain sizes) and frequencies (resolutions) of importance to nuclear explosion monitoring. The objective of this research is to develop and improve methods for seismic simulation in fully 3D earth models to improve nuclear explosion monitoring. Specifically, research is directed along three thrusts: modeling of shock-wave propagation with hydrodynamic methods; modeling of elastic propagation near shallow explosions and earthquakes, including the effect of 3D volumetric structure and free-surface topography; and regional broadband waveform modeling. This effort relies on numerical methods for 3D wave phenomena implemented in computer codes running on massively parallel computers. These capabilities allow us to investigate source and propagation phenomenology of explosion sources and understand waveform data from specific events of interest.