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Slow Stick-Slip Failure in Halite Gouge Caused by Brittle-Plastic Fault Heterogeneity.
- Source :
- Geochemistry, Geophysics, Geosystems: G3; Sep2020, Vol. 21 Issue 9, p1-13, 13p
- Publication Year :
- 2020
-
Abstract
- Slow earthquakes, including low-frequency earthquakes and tremor, occur in the brittle-ductile (plastic) transition zone on plate boundary faults. To understand how transitions in deformation mechanisms can influence seismic behavior, we conducted stick-slip experiments on halite gouge at normal stresses (σ<subscript>n</subscript>) of 8 to 113 MPa. In the brittle regime (σ<subscript>n</subscript> ≤ 18 MPa), the halite gouge showed fast and regular stick-slip associated with velocity-weakening behavior. In contrast, increasing the normal stress within the semibrittle regime (σ<subscript>n</subscript> ≥ 27 MPa) led to a significant decrease in slip velocity and stress drop, which was associated with a transition from velocity-weakening to velocity-strengthening behavior. Local stress measurements along the simulated faults, made using strain gauges, revealed that the critical nucleation length (L<subscript>c</subscript>) increased with increasing normal stress. Macrostructural and microstructural observations showed that the transition from fast dynamic slip to slow quasi-static slip could be attributed to an increasing contribution from semibrittle/plastic deformation occurring within domains that are heterogeneously distributed within the gouge layer. Our findings suggest that brittle-plastic fault heterogeneity, which may be generated by spatial variations in pore fluid pressure and/or lithology, contributes to the emergence of slow earthquakes. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 15252027
- Volume :
- 21
- Issue :
- 9
- Database :
- Complementary Index
- Journal :
- Geochemistry, Geophysics, Geosystems: G3
- Publication Type :
- Academic Journal
- Accession number :
- 146114857
- Full Text :
- https://doi.org/10.1029/2020GC009165