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Off-fault deformation feedback and strain localization precursor during laboratory earthquakes
Gabriel G Meyer1, Carolina Giorgetti1,2, Simon Guérin-Marthe1
1LEMR ENAC, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
Communications Earth & Environment
|October 14, 2024
Summary
Off-fault deformation and strain localization precede earthquakes. This study links these phenomena to earthquake nucleation, suggesting they are reliable early warning signs.
Area of Science:
- Geophysics
- Seismology
- Rock Mechanics
Background:
- Seismological observations suggest off-fault strain localization and foreshock migration may precede earthquakes.
- The precise mechanisms linking these precursors to earthquake nucleation remain poorly understood.
Purpose of the Study:
- To investigate the relationship between stick-slip nucleation and off-fault deformation.
- To determine if off-fault deformation influences earthquake nucleation processes.
Main Methods:
- Conducted state-of-the-art friction experiments using an oil-confined biaxial shear apparatus.
- Simulated earthquake nucleation and slip events under controlled laboratory conditions.
Main Results:
- A direct link was found between stick-slip nucleation and off-fault deformation in conditionally unstable faults (a-b < 0).
- Inelastic off-fault deformation was observed to decrease surrounding rock stiffness, promoting earthquake nucleation.
- Precursory strain localization around the fault during stick-slip cycles was observed in laboratory experiments.
Conclusions:
- Volumetric deformation processes are likely key factors in the nucleation of large earthquakes.
- Observed strain localization serves as a reliable indicator for impending large earthquakes.
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