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MCMC-MTpy: A Python Package for Simultaneous Inversion of Source Location, Focal Mechanism and Rupture Directivity

The source parameters (Source Location, Focal Mechanism, and Rupture Directivity) are of key importance in seismic source studies and seismic hazard assessments. Generally, different source parameters are estimated separately. Separate inversion of source parameters may induce some inconsistence. In this study, we proposed a new Bayesian inversion method MCMC-MTpy. MCMC-MTpy takes phase (both P and S) travel times, first arrival P-wave polarity and the waveform as input to invert the source location, focal Mechanism, and rupture directivity iteratively.

Different weighting factors were used in different stage of the inversion. First the highest weight was assigned to the travel time objective function, which effectively constrains the source location. Then higher weight was put on the waveform and the polarity to estimate the focal mechanism. The direction of epicentral and the centroid of the focal mechanism is used to describe the rupture directivity.

Synthetic tests suggest the newly package can effectively retrieve the source parameters. The effect of weight strategy was also investigated through synthetic tests. Both the package and Application Program Interface for Green’s Function calculation were written in Python and will be accessible soon on the author’s Github site.

Presenting Author: Fu Yin

Student Presenter: Yes

Day: 4/22/2021

Time: 3:45 PM - 4:45 PM Pacific

Additional Authors