Preliminary dynamic rupture simulations of the July 2019 M6.4 and M7.1 Ridgecrest, California, earthquakes

Julian C. Lozos, & Ruth A. Harris

Published August 6, 2019, SCEC Contribution #9348, 2019 SCEC Annual Meeting Poster #279

The primary events of the 2019 Ridgecrest earthquake sequence were a M6.4 earthquake with left-lateral surface rupture that also produced aftershocks on a conjugate right-lateral fault, followed 34 hours later by a M7.1 earthquake that ruptured the same right-lateral fault. The geometry and timing of these earthquakes raises several questions about fault interactions, including: what conditions promoted conjugate rupture in the M6.4 and how much of the right-lateral fault was involved; how influential were the stress changes from the M6.4 on the M7.1 rupture pattern; and what led to apparent re-rupture of a section of the right-lateral fault in the M7.1 earthquake? We use dynamic rupture modeling to address these questions. We find that a homogeneous regional stress field resolved onto a fault geometry inferred from satellite geodesy and field observations produces conjugate ruptures consistent with observations of the M6.4 earthquake. However, the same initial stresses do not produce any simulated ruptures that are comparable to the M7.1 earthquake, implying that the stress changes from the M6.4 may have played a significant role in promoting the M7.1 rupture. We will also discuss a case in which we use the final stresses from the M6.4 earthquake model as initial stresses for the M7.1 rupture, then examine the stressing effects that both Ridgecrest earthquakes had on the nearby Garlock Fault.

Key Words
Ridgecrest earthquakes, 2019 Ridgecrest sequence, dynamic rupture modeling, fault interactions

Citation
Lozos, J. C., & Harris, R. A. (2019, 08). Preliminary dynamic rupture simulations of the July 2019 M6.4 and M7.1 Ridgecrest, California, earthquakes. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Ridgecrest Earthquakes