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Isotropic Source Components of Events in the 2019 Ridgecrest, California, Earthquake Sequence
Author(s) -
Cheng Yifang,
Wang Xin,
Zhan Zhongwen,
BenZion Yehuda
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl094515
Subject(s) - seismology , isotropy , geology , foreshock , waveform , shear (geology) , dipole , fault (geology) , aftershock , attenuation , physics , petrology , quantum mechanics , optics , voltage
We investigate the non‐double‐couple components of 224 M ≥ 3.0 earthquakes in the 2019 M w 7.1 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 3‐D velocity and attenuation models. 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 between the M w 6.4 foreshock and 1 day after the M w 7.1 mainshock and are mainly distributed around the rupture ends and fault intersections. The percentage of isotropic components is reduced considerably 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.