Source estimation for wave equations with uncertain parameters
Source estimation is a fundamental ingredient of Full Waveform Inversion (FWI). In such seismic inversion methods wavelet intensity and phase spectra are usually estimated statistically although for the FWI formulation as a nonlinear least-squares optimization problem it can naturally be incorporated to the workflow. Modern approaches for source estimation consider robust misfit functions leading to the well known robust FWI method. The present work uses synthetic data generated from a high order spectral element forward solver to produce observed data which in turn are used to estimate the intensity and the location of the point seismic source term of the original elastic wave PDE. A min-max filter approach is used to convert the original source estimation problem into a state problem conditioned to the observations and a non-standard uncertainty description. The resulting numerical scheme uses an implicit midpoint method to solve, in parallel, the chosen 2D and 3D numerical examples running on an IBM Blue Gene/Q using a grid defined by approximately sixteen thousand 5th order elements, resulting in a total of approximately 6.5 million degrees of freedom.