DOI: 10.5061/dryad.np5hqc06w
title: Cohabitation of slow and moderate-sized earthquakes in blueschist-facies linked to fault microstructure and rheology

description: We explore how slow earthquakes and
 moderate-sized intraplate earthquakes cohabit in blueschist-facies at
 intermediate-depth. We measure friction on blueschist gouges at
 elevated temperatures (100-500℃), effective normal stresses
 (60-220 MPa) and fluid pressures (30-75
 MPa) to represent conditions along the descending slab
 and to link observed rheology to microtextural evolution.
 We identify a transition into potentially
 unstable rheologies at elevated temperatures
 &gt;200℃ - meeting the conditions necessary for generation of
 earthquake instabilities at blueschist-facies depths. This
 transition is controlled by a mechanism of thermally-activated
 dissolution creep indicated by the observed presence of dissolved
 glaucophane and suggestive of dilation-suppressing
 fluid-assisted mass transfer processes. Reducing effective normal stress
 results in increasingly unstable behavior as evident
 in dynamic stick-slip. This is driven by an increase in effective
 fault stiffness k'c as a result of enhanced shear
 localization in the gouge fabric. However, this rupture
 growth, promoted by lower effective
 stress, may be limited by the
 increase in fluid pressure which independently promotes
 stable deformation with slip-dependent strengthening. From these multiple competing feedbacks, we infer that slip instabilities nucleated within blueschist grade slabs should favor earthquakes of limited-size. This is consistent with observations that both slow and moderate-sized dynamic earthquakes cohabit the cold subducting slab at blueschist-facies depths.
description: # Cohabitation of slow and moderate-sized earthquakes in blueschist-facies
 linked to fault microstructure and rheology Dataset DOI:
 [10.5061/dryad.np5hqc06w](10.5061/dryad.np5hqc06w) ## Description of the
 data and file structure                                                   
     The friction-displacement data for all shear experiments on blueschist
 gouges. **File list and description (files found within DataS1.zip)**
 Huang_et_al_2025_BS_100.xlsx – The shear displacement (mm) (column 1) and
 coefficient of friction (dimensionless) (column 2) data for Experiment
 BS-100. Huang_et_al_2025_BS_200.xlsx – The shear displacement (mm) (column
 1) and coefficient of friction (dimensionless) (column 2) data for
 Experiment BS-200. Huang_et_al_2025_BS_300.xlsx – The shear displacement
 (mm) (column 1) and coefficient of friction (dimensionless) (column 2)
 data for Experiment BS-300. Huang_et_al_2025_BS_350.xlsx – The shear
 displacement (mm) (column 1) and coefficient of friction (dimensionless)
 (column 2) data for Experiment BS-350. Huang_et_al_2025_BS_400.xlsx – The
 shear displacement (mm) (column 1) and coefficient of friction
 (dimensionless) (column 2) data for Experiment BS-400.
 Huang_et_al_2025_BS_500.xlsx – The shear displacement (mm) (column 1) and
 coefficient of friction (dimensionless) (column 2) data for Experiment
 BS-500. Huang_et_al_2025_BS_C110.xlsx – The shear displacement (mm)
 (column 1) and coefficient of friction (dimensionless) (column 2) data for
 Experiment BS-C110. Huang_et_al_2025_BS_C65.xlsx – The shear displacement
 (mm) (column 1) and coefficient of friction (dimensionless) (column 2)
 data for Experiment BS-C65. Huang_et_al_2025_BS_300_P75.xlsx – The shear
 displacement (mm) (column 1) and coefficient of friction (dimensionless)
 (column 2) data for Experiment BS-300-P75.
 Huang_et_al_2025_BS_C110_P75.xlsx – The shear displacement (mm) (column 1)
 and coefficient of friction (dimensionless) (column 2) data for Experiment
 BS-C110-P75.