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- Title
Carbonate Fault Mirrors With Extremely Low Frictional Healing Rates: A Possible Source of Aseismic Creep.
- Authors
Park, Yohan; Takehiro Hirose; Jin-Han Ree
- Abstract
Frictional healing of faults is a key mechanism controlling fault strength recovery, which enables the development of repeating earthquake cycles. Carbonate fault rocks are commonly characterized by shiny mirror-like surfaces, sometimes referred to as fault mirrors. Despite the prevalence of fault mirrors in both natural and experimental fault rocks, their frictional healing behavior has not yet been studied. We measured frictional healing rates of experimentally simulated carbonate fault mirrors and found them to be an order of magnitude lower than those of other carbonate fault rocks. Microstructurally, the fault zone of fault mirror specimens is characterized by densely packed sintered nanogouges. We infer that this tight nanograin structure hinders the chemical and physical processes that cause frictional healing. Fault mirrors showing extremely low frictional healing rates are likely to creep aseismically. Plain Language Summary An increase in the static friction between two stationary bodies, called "frictional healing," may be a prerequisite for repetitive earthquake cycles. Frictional healing allows a fault to regain energy following an earthquake, thus allowing repeating earthquakes. Natural and experimental fault rocks commonly have shiny, mirror-like fault surfaces, sometimes referred to as "fault mirrors." In this study, we simulated carbonate fault mirrors experimentally, revealing that the frictional healing rate of the simulated fault mirrors is much lower than that of typical carbonate fault rocks. This indicates that frictional healing depends not only on the mineralogy but also on the physical structure of a fault rock. Because a low frictional healing rate hinders stress recovery, carbonate fault mirrors in an active fault zone may creep aseismically.
- Subjects
CARBONATES; CARBONATE rocks; FAULT zones; STATIC friction; HEALING; MIRRORS
- Publication
Geophysical Research Letters, 2021, Vol 48, Issue 11, p1
- ISSN
0094-8276
- Publication type
Article
- DOI
10.1029/2021GL093749