Finite source modeling of the 2019 Ridgecrest aftershock sequence

Jose A. Magana, Douglas S. Dreger, & Taka'aki Taira

Published August 14, 2020, SCEC Contribution #10584, 2020 SCEC Annual Meeting Poster #118 (PDF)

The connection between the strength of tectonic faults and the earthquake rupture is central to studies of the physics of earthquakes. Ross et al. [2019] report that much of the sequence occurred on a complex network of orthogonally oriented faults that were previously unknown, and finite-source models of the M6.1 foreshock and M7.0 mainshock (e.g. Kang et al., 2020) report slow rupture velocity suggesting a relatively high fracture energy in rupturing an immature and geometrically complex fault. Here we investigate the stress drop of the aftershocks comparing with estimates from finite source models of the foreshock and mainshock. We use an empirical Greens function (EGF) derived moment rate function inversion method (Mori and Hartzell, 1990; Dreger, 1996) to determine the causative rupture plane of aftershocks, the slip distribution and the stress change (e.g. Ripperger and Mai, 2004). Possible EGF events will be identified through relative event location, cross-correlation, and recovery of moment rate pulses from the EGF deconvolution. Seismic moment tensor solutions will be reviewed or determined as needed for a specific target and EGF events, and both possible nodal planes will be tested in the moment rate inversion (e.g. Mori and Hartzell, 1990). The derived best fitting fault planes and slip distributions will be used to determine the stress change (Ripperger and Mai, 2004). We will explore the rupture area and slip scaling of the sequence and compare with existing scaling relationships and results for different earthquake sequences.

Citation
Magana, J. A., Dreger, D. S., & Taira, T. (2020, 08). Finite source modeling of the 2019 Ridgecrest aftershock sequence. Poster Presentation at 2020 SCEC Annual Meeting.

Related Projects & Working Groups
Stress and Deformation Over Time (SDOT)