EGU2020-15268
https://doi.org/10.5194/egusphere-egu2020-15268
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Untangling the dynamics of the 2019 Ridgecrest sequence by integrated dynamic rupture and Coulomb stress modeling across an immature 3D conjugate fault network

Alice-Agnes Gabriel1, Taufiqurrahman Taufiqurrahman1, Sara Carena1, Alessandro Verdecchia2, Bo Li1, Duo Li1, Thomas Ulrich1, Frantisek Gallovic3, and Sara Aniko Wirp1
Alice-Agnes Gabriel et al.
  • 1LMU Munich, Geophysics, Department of Earth and Environmental Sciences, Munich, Germany (gabriel@geophysik.uni-muenchen.de)
  • 2McGill University, Department of Earth and Planetary Sciences, Montreal, Canada
  • 3Charles University, Faculty of Mathematics and Physics, Department of Geophysics, Prague, Czech Republic

We present combined 3D dynamic rupture scenarios of the 2019 Mw6.4 Searles Valley and Mw7.1 Ridgecrest earthquakes closely constrained by observations, incorporating complex subsurface material properties, high-resolution topography and off-fault plastic deformation empowered by supercomputing. A detailed 3D non-vertical fault model of the active quasi-orthogonal intersecting fault network is built by integrating relocated aftershocks and surface ruptures constrained by space geodesy and field observations. All faults are exposed to a 3D SCEC community stress model as well as long- and short-term static and dynamic stress transfers, which impact rupture dynamics, particularly in the vicinity of complexities in fault geometry.

By assuming apparently weak faults due to the effect of rapid velocity-weakening friction and elevated fluid pressure, we determine initial stresses and fault strength. Multi-fault rupture directivity and velocity of both events are constrained by aftershock calibrated back-projection. In the presented scenario two conjugate faults simultaneously rupture in the Mw6.4 event, while only the SW-segment breaks the surface. The Mw7.1 event experiences the full final state of stress (dynamic plus static effects) of the Searles Valley scenario, leading to complex rupture including re-activation of the conjugate Mw6.4 segment, mixed crack and pulse-like propagation, tunneling beneath the fault intersection and choosing one Southern branch only. Both events exhibit a high dynamic stress drop reflecting the immature fault system. The foreshock induces a considerable Coulomb stress change in the Mw7.1 hypocentral region; however, not enough to trigger rupture across the stress-shadowed main fault. Both scenarios match key observations including magnitude, rupture speed, directivity, off-fault damage, slip distribution from kinematic inversion, teleseismic waveforms, GPS, and InSAR ground deformation; while shedding light on geometric, strength and stress factors governing the complex rupture evolution and interaction of the Ridgecrest sequence.

How to cite: Gabriel, A.-A., Taufiqurrahman, T., Carena, S., Verdecchia, A., Li, B., Li, D., Ulrich, T., Gallovic, F., and Wirp, S. A.: Untangling the dynamics of the 2019 Ridgecrest sequence by integrated dynamic rupture and Coulomb stress modeling across an immature 3D conjugate fault network, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15268, https://doi.org/10.5194/egusphere-egu2020-15268, 2020

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