A time-domain earthquake full waveform moment tensor inversion system

EMANUEL TRABES; SILVANA SPAGNOTTO; RAUL LOPRESTI; ORLANDO ALVAREZ; JULIO DONDO GAZZANO; CARLOS FEDERICO SOSA PAEZ

Athenas

Congreso; 37th General Assembly (GA) of the European Seismological Commission; 2021

ESC General Assembly

In this work, we developed a system to perform joint inversion of an earthquakes full moment tensor, its centroid location and centroid time. Our system is based on a time-domain full waveform inversion methodology. Performing the inversion in the time-domain allows us to utilize several source frequencies at once, unlike frequency-domain inversion. We utilized the levenberg-marquardt algorithm to perform a nonlinear optimization for all of the 10 parameters ( 6 for the moment tensor, 3 for the spatial locations and 1 for time). Our system outputs the estimated parameters of the earthquake, as well as the gauss-newton approximation of the hessian. The hessian allows our method to converge in only a few iterations, and also allows us to perform uncertainty analysis of the estimated parameters. We based our system in a fast time-domain forward simulation system recently developed in our group. This simulation system was programmed using the GLSL shading language, thus is able to run in the GPU of any relatively modern PC or notebook. Our system does not require saving to disk the forward wavefield, thus saving costly CPU-GPU memory bandwidth. We show the performance and accuracy of our system with an inversion of a well-known earthquake that took place in the Cuban shores in 2017.