Isotropic source components of events in the 2019 Ridgecrest, California, earthquake sequence

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

Under Review June 24, 2021, SCEC Contribution #11025

We investigate non-double-couple components of 224 M ≥ 3 earthquakes in the 2019 M7.1 Ridgecrest sequence, which occurred on a complex fault system in the Eastern California Shear Zone. Full moment tensors are derived using waveform data from near-fault and regional stations with a generalized cut-and-paste inversion and a 3D velocity model. The results show limited Compensated Linear Vector Dipole components but considerable explosive isotropic components (5-15% of the total moments) for approximately 50 earthquakes. Most of these events occur in the first two days after the M7.1 mainshocks and are mainly distributed around the rupture ends and fault intersections. The percentage of isotropic components is reduced when data recorded by near-fault stations are not included in the inversions, highlighting the importance of near-fault data. The results suggest that high-frequency damage-related radiation and other local dilatational processes are responsible for the observed isotropic source terms.

Citation
Cheng, Y., Wang, X., Zhan, Z., & Ben-Zion, Y. (2021). Isotropic source components of events in the 2019 Ridgecrest, California, earthquake sequence. Geophysical Research Letters, (under review).