Experimental study on the influences of fault contact distribution on the speed of stick-slip instability
Abstract
Experimental study on the factors affecting the speed of stick-slip instability is helpful to understand the origins of slow slip events. We found that under the same conditions, the speed of stick-slip instability of the granodiorite is affected by the fault contact distribution. Namely, the fault with homogeneous contact distribution produces slow stick-slip events, while the fault with heterogeneous contact distribution generates fast stick-slip events. We observed the evolution of the stick-slip events generated by faults with homogeneous as well as heterogeneous contact distributions via repeated loading-and-unloading cycles and found that the loading frame induced stress concentration effect at the ends of the fault finally appeared in the both samples. During this process, the stick-slip instability of the homogeneous contact fault evolved from slow to fast, while fast, slow, and fast stick-slip events successively occurred in the heterogeneous contact fault. From the analysis of the pressure sensitive films, we found that contact concentrated in the two ends of the original homogeneous contact fault after the repeated loading-and-unloading cycles, which indicated the fault underwent a process of transition from homogeneous to heterogeneous contact. Moreover, such contact concentration at fault ends was also found in the original heterogeneous contact fault, which were characterized by weak contact at both ends before the experiments, indicating that the fault underwent a process of transition from heterogeneous to homogeneous and then to heterogeneous contact. Therefore, we propose that the fault contact distribution can be a factor controlling the speed of stick-slip instability of granodiorite. In addition, the nucleation processes of both fast and slow stick-slip events during the experiments were observed via a high speed camera combined with a digital image correlation method, which were used to analyze the mechanism of the effects of fault contact distribution based on the rate- and state-dependent friction constitutive law.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.S13F0498Z
- Keywords:
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- 7209 Earthquake dynamics;
- SEISMOLOGY;
- 7215 Earthquake source observations;
- SEISMOLOGY;
- 7230 Seismicity and tectonics;
- SEISMOLOGY;
- 8170 Subduction zone processes;
- TECTONOPHYSICS