~ This multifaceted, group project involves 5 PhD students, one research associate, and the PI in the Center for Lithospheric Studies at the University of Texas at Dallas. The main focus is conceptualization, implementation, testing, documentation and application of new parallel algorithms for 3-D numerical simulation, imaging and inversion of 3 and 9 component seismic wavefields. The main application is characterization of oil and gas reservoirs and the fluids contained in them in the hydraulic fracturing environment, and so include anisotropic and viscoelastic media; these parametrizations have up to 21 elastic constants at each grid point n the 3-D numerical models and so present significant computational challenges. Data sets are typically multi- terrabytes in size. A new direction in 2019-20 is application of machine learning to seismic full-waveform inversion. Specific sub-projects that are currently active in this context and tre at various stages of develoment/testing, and that need access to serious parallel computing include: 1) data mining as a new paradigm for seismic data inversion; model gradients and updates via machine learning (nearing completion) 2) Rate and state flow and deformation simulation of microseismicity with elastic emission wavefield synthesis (nearing completion) 3) Source-independent inversion of elastic seismic wavefields by minimizing both data residuals and wavefield snapshot residuals (submitted for publication) 4) frequency-domain 3-D imaging and concurrent full- wavefield inversion from body wave reflections and Rayleigh and Love surface waves (submitted for publication) 5) Limitations to wavenumber recovery in Full Waveform inversion of elastic seismic data (nearing completion) 6) Concurrent full-waveform inversion of Rayleigh and body waves, with application to field data (submitted for publication) 7) A test of tomographic imaging of a field data set from California for 3D velocity, attenuation and anisotropy (new project in 2010) 8) A test of full wavefield imaging of wave attenuation for a marine field data set (new project in 2020) 9) Imaging of an earthquake source rupture (same data set as item 8 above) (new project in 2020)
