This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1029/2019GL085408. This is version 1 of this Preprint.
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Abstract
The increased seismic activity of the last ~10 years in Changning county of Sichuan Province comprised just small (mostly ML < 5.0) injection-induced earthquakes. The MW 5.7 earthquake of June 17, 2019 is the largest event ever reported there. Moment tensor of the mainshock was remarkably dominated by a compensated linear vector dipole. We resolve its fine structure showing it was a doublet, allowing approximation by a thrust- and strike-slip subevent. The mainshock nucleated as thrust faulting, which (together with the largest aftershocks) can be linked with previously known reverse faults, favorably oriented to regional stress field. Contrarily, the strike-slip segment of the mainshock, less favorably oriented, was probably facilitated by elevated pore pressure due to previous injections. Shallow active strike-slip faulting, not yet mapped in the region, is a new feature, important for future hazard assessment.
DOI
https://doi.org/10.31223/osf.io/nzseb
Subjects
Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Keywords
Earthquake doublet, Injection-induced events, Multiple-point source model, Non-double-couple, Sub-optimally oriented faults
Dates
Published: 2020-02-12 16:10
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