Linking laboratory with in-situ observations to improve the understanding of fault slip behaviour during fluid pressurization
Abstract
It is well recognized that fluids play a fundamental role during the seismic cycle of tectonic faults. Following the effective stress principle, an increase in fluid pressure can favor fault reactivation because it decreases the effective stress that clamps the fault in place. However, understanding the interaction between the intrinsic frictional properties of fault and the stress changes caused by fluid pressure evolution is a long-standing challenge. The characterization of the hydro-mechanical coupling of faults has important implications in our understanding of natural phenomena, including landslides, and human induced earthquakes. In an effort to shed light on these processes, in the past few years, we have first designed specific laboratory experiments to characterize the potential for fault reactivation by means of fluid pressurization and then compared laboratory results with in-situ observations. By developing unconventional creep experiments, where the fault is held under constant boundary stresses and reactivated by increasing fluid pressure, we show that it exist a strong hydro-mechanical coupling resulting in a variety of fault slip behaviors, depending on fault mineralogical composition, fault zone structure and hydrological properties, ranging from slow accelerations to dynamic fault slip. Second, by using fault gouge recovered from in-situ decametric scale experiments or from active giant landslides we have reproduced in the laboratory the stress conditions and evolving fluid pressure that have caused fault to slip and compared, through predictive models, to the in-situ observations. Interestingly we find that at the laboratory scale we can depict the slip behavior observed in nature representing a good proxy for the observed in-situ behavior. This upscaling is a fundamental step to shed light into the physical processes at the origin of fault reactivation by fluid pressurization.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMMR030..03S
- Keywords:
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- 3994 Instruments and techniques;
- MINERAL PHYSICS;
- 7209 Earthquake dynamics;
- SEISMOLOGY;
- 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICS;
- 8163 Rheology and friction of fault zones;
- TECTONOPHYSICS