학술논문

The Stability Transition From Stable to Unstable Frictional Slip With Finite Pore Pressure
Document Type
article
Source
Geophysical Research Letters, Vol 51, Iss 1, Pp n/a-n/a (2024)
Subject
slow slip earthquakes
pore fluid pressure
frictional stability
dilatancy
Geophysics. Cosmic physics
QC801-809
Language
English
ISSN
1944-8007
0094-8276
Abstract
Abstract Pore fluids are ubiquitous throughout the lithosphere and are commonly invoked as the cause of induced seismicity and slow earthquakes. We perform lab experiments to address these questions for drained fault conditions and low pore pressure. We shear simulated faults at effective normal stress σn′ of 20 MPa and pore pressures Pp from 1 to 4 MPa. We document the full range of lab earthquake behaviors from slow slip to elasto‐dynamic rupture and show that slow slip can be explained by the slip rate dependence of the critical rheologic stiffness without dilatancy hardening or other fluid effects. Our fault permeabilities ranges from 10−18 to 10−17 m2 with an initial porosity of 0.1 and estimated fluid diffusion time ≈1 s. Slow slip and quasi‐dynamic fault motion may arise from high Pp at higher pressures but dilatancy strengthening is not a general requirement.