Isotropic source components of events in the 2019 Ridgecrest earthquake sequence

Xin Wang, Yifang Cheng, Zhongwen Zhan, & Yehuda Ben-Zion

Submitted August 11, 2020, SCEC Contribution #10374, 2020 SCEC Annual Meeting Poster #068

We investigate source mechanisms of 256 M3.5+ aftershocks of the 2019 M7.1 Ridgecrest earthquake, which ruptured a complex fault system in the Eastern California Shear Zone. The full moment tensors are derived with a generalized “Cut and Paste” inversion using a 3D velocity model and regional (<=100 km) three-component broadband waveform data. We perform multiple inversions of moment tensors using waveforms recorded by stations within different epicentral distance ranges, with uncertainties of source parameters estimated by a bootstrapping method. The results show that about 60 aftershocks have significant isotropic components that are about 5%-15% of the total moments of the events. In contrast, most events do not have statistically significant Compensated-Linear-Vector-Dipoles components. Earthquakes with large isotropic components are mainly distributed around rupture ends, intersection, and the areas of high mainshock coseismic slip, suggesting damage-related isotropic radiations. The values of isotropic components increase by adding more waveforms from near-event stations into the inversions, highlighting the importance of nearfield data in understanding realistic source behaviors.

Key Words
2019 Ridgecrest; Moment Tensor; Isotropic components

Wang, X., Cheng, Y., Zhan, Z., & Ben-Zion, Y. (2020, 08). Isotropic source components of events in the 2019 Ridgecrest earthquake sequence. Poster Presentation at 2020 SCEC Annual Meeting.

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