On-the-Fly Full Hessian Kernel Calculations Based upon Seismic-Wave Simulations

Abstract Full waveform inversion or adjoint tomography has routinely been performed to image the internal structure of Earth at high resolution. This is typically done using Fréchet kernels and approximate Hessian inverse because high-computational cost computing storing full Hessian. Alternatively, can be used improve resolutions convergence rates, as well possibly mitigate interparameter trade-offs. The storage requirements kernel calculations reduced by compression methods, but often a price accuracy depending on factor. Here, we present open-source codes compute both fly in computer random access memory (RAM) through simultaneously solving four wave equations, which call Quad Spectral-Element Method (QuadSEM). By recomputing two forward fields same time that are calculated during simulation, QuadSEM constructs exact fields. In addition, also implement an alternative approach based classical wavefield method (WSM), stores wavefields every kth (k≥1) timestep simulation reads required back into for construction. Both computed WSM code, only doubling computational compared with computation alone. Compared WSM, reduce disk space input/output three orders magnitude presented examples use 15,000 timesteps. Numerical demonstrate functionality provided this contribution.