Earthquake nucleation in weak subducted carbonates.

Kurzawski, Robert M., Stipp, Michael, Niemeijer, André R., Spiers, Christopher J. and Behrmann, Jan H. (2016) Earthquake nucleation in weak subducted carbonates. Nature Geoscience, 9 (9). pp. 717-722. DOI 10.1038/ngeo2774.

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Abstract

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.

Document Type: Article
Additional Information: WOS:000383283700020
Keywords: DV JOIDES Resolution, IODP Expeditions 334 and 344
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1038/ngeo2774
ISSN: 1752-0894
Projects: IODP
Expeditions/Models/Experiments:
Date Deposited: 09 Aug 2016 06:46
Last Modified: 01 Feb 2019 15:10
URI: http://oceanrep.geomar.de/id/eprint/33546

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