Work

Rapid Normal Stress Oscillations Cause Weakening and Anelastic Dilation in Gouge‐Bearing Faults

Year: 2024

Type: article

Abstract: Fault normal stress ( σ n ) changes dynamically during earthquakes. However, the impact of these changes on fault strength is poorly understood. We explore the effects of rapidly varying σ n by conducting rotary‐shear experiments on simulated fault gouges at 1 μm/s, under well‐drained, hydrothermal conditions. Our results show both elastic and anelastic (time‐dependent but recoverable) changes in gouge layer thickness in response to step changes and sinusoidal oscillations in σ n . In particular, we observe dilation associated with marked weakening during ongoing σ n ‐oscillations at frequencies >0.1 Hz. Moreover, recovery of shear stress after such oscillations is accompanied by transient (anelastic) compaction. We propose a microphysically based friction model that explains most of the observations made, including the effects of temperature and step versus sinusoidal perturbation modes. Our results highlight that σ n ‐oscillations above a specific frequency threshold, controlled by the loading regime and frictional properties of the fault, may enhance seismic hazards.

Source: Geophysical Research Letters

DOI: 10.1029/2024gl109755

Authors: Jianye Chen, Andre R. Niemeijer, Christopher J. Spiers

Institutions: Utrecht University, Institute of Geology, China Earthquake Administration, State Key Laboratory of Earthquake Dynamics, China Earthquake Administration, Delft University of Technology

Language: English

Topic: earthquake and tectonic studies

Subfield: Geophysics

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,900

Funders: National Science Foundation, Nederlandse Organisatie voor Wetenschappelijk Onderzoek