| Autor: |
Kurzawski, Robert M., Stipp, Michael, Niemeijer, André R., Spiers, Chirstopher J., Behrmann, Jan H. |
| Přispěvatelé: |
Experimental rock deformation, ERC-SEISMIC: Slip and earthquake nucleation in experimental and numerical simulations: a multi-scale, integrated and coupled approach, NWO-VIDI: Slip and Earthquake Nucleation in Experimental and Numerical Simulations: a Multi-scale, Integrated and Coupled Approach |
| Jazyk: |
angličtina |
| Rok vydání: |
2016 |
| Popis: |
Ocean-floor carbonate- and clay-rich sediments form major inputs to subduction zones, especially at low-latitude convergent plate margins. Therefore, knowledge of their frictional behaviour is fundamental for understanding plate-boundary earthquakes. Here we report results of mechanical tests performed on simulated fault gouges prepared from ocean-floor carbonates and clays, cored during IODP drilling offshore Costa Rica. Clay-rich gouges show internal friction coefficients (that is, the slope of linearized shear stress versus normal stress data) of μint = 0.44 − 0.56, irrespective of temperature and pore-fluid pressure (Pf). By contrast, μint for the carbonate gouge strongly depends on temperature and pore-fluid pressure, with μint decreasing dramatically from 0.84 at room temperature and Pf = 20 MPa to 0.27 at T = 140 °C and Pf = 120 MPa. This effect provides a fundamental mechanism of shear localization and earthquake generation in subduction zones, and makes carbonates likely nucleation sites for plate-boundary earthquakes. Our results imply that rupture nucleation is prompted by a combination of temperature-controlled frictional instability and temperature- and pore-pressure-dependent weakening of calcareous fault gouges. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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