Carbonate Fault Mirrors With Extremely Low Frictional Healing Rates: A Possible Source of Aseismic Creep

Yohan Park, Takehiro Hirose, Jin Han Ree

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish
Article numbere2021GL093749
JournalGeophysical Research Letters
Volume48
Issue number11
DOIs
Publication statusPublished - 2021 Jun 16

Keywords

  • earthquake cycle
  • fault mirror
  • frictional healing
  • nanogouge

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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