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The Stability Transition from Stable to Unstable Frictional Slip with Finite Pore Pressure
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  • Raphael Affinito,
  • Clay Wood,
  • samson marty,
  • Elsworth Derek,
  • Chris Marone
Raphael Affinito
The Pennsylvania State University

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Clay Wood
Penn State University
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samson marty
Rock and Sediment mechanics laboratory - PSU
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Elsworth Derek
The Pennsylvania State University
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Chris Marone
Pennsylvania State University
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Pore fluids are ubiquitous throughout the lithosphere and are commonly cited as the cause of slow-slip and complex modes of tectonic faulting. We investigate the role of fluids for slow-slip and the frictional stability transition and find that the mode of fault slip is mainly unaffected by pore pressures. We shear samples at effective normal stress (σ’n) of 20 MPa and pore pressures Pp from 1 to 4 MPa. The lab fault zones are 3 mm thick and composed of quartz powder with median grain size of 10 µm. Fault permeability evolves from 10-17 to 10-19 m2 over shear strains up to 26. Under these conditions, dilatancy strengthening is minimal. Slow slip may arise from dilatancy strengthening at higher fluid pressures but for the conditions of our experiments slip rate-dependent changes in the critical rate of frictional weakening are sufficient to explain slow-slip and the stability transition to dynamic rupture.
16 Mar 2023Submitted to ESS Open Archive
16 Mar 2023Published in ESS Open Archive