Effects of normal stress and shear velocity on the frictional healing behavior of halite fault gouge

Abstract

The distinctive characteristics exhibited by the aftershocks of Ms6.0 induced earthquakes in Changning, Sichuan, China, have attracted significant attention. The prevalence of salt rock (halite) in this area is closely associated with induced seismic events. The present study was conducted to examine the role of halite in frictional properties. To this end, laboratory measurements were taken for simulated fault gouge composed of halite. Slide-hold-slide (SHS) shear experiments were performed on gouges with grain size <106 μm at constant normal stress from 5 MPa to 30 MPa and constant shear velocity in the range of 1–10 μm/s. Halite gouge shows higher frictional strength and frictional healing rate than most minerals. The results reveal that the fault within halite can potentially generate intense seismic events and more significant aftershocks. An increase in normal stress leads to a reduction in frictional healing, with frictional strength initially increasing and then decreasing. The elevated shear velocity following fault activation facilitates fault dilation, diminishes the frictional strength of the fault, and contributes to fault healing during the inter-seismic period. The aforementioned findings will contribute to a comprehensive understanding of the potential for the healing property of induced seismicity on faults containing halite, particularly in the Changning region of China.