Subduction megathrust creep governed by pressure solution and frictional-viscous flow

Fagereng, Ake ORCID: https://orcid.org/0000-0001-6335-8534 and den Hartog, Sabine A. M. 2017. Subduction megathrust creep governed by pressure solution and frictional-viscous flow. Nature Geoscience 10 (1) , pp. 51-57. 10.1038/ngeo2857

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Abstract

Subduction megathrust slip speeds range from slow creep at plate convergence rates (centimetres per year) to seismic slip rates (metres per second) in the largest earthquakes on Earth. The deformation mechanisms controlling whether fast slip or slow creep occurs, however, remain unclear. Here, we present evidence that pressure solution creep (fluid-assisted stress driven mass transfer) is an important deformation mechanism in megathrust faults. We quantify megathrust strength using a laboratory-constrained microphysical model for fault friction, involving viscous pressure solution and frictional sliding. We find that at plate-boundary deformation rates, aseismic, frictional–viscous flow is the preferred deformation mechanism at temperatures above 100 °C. The model thus predicts aseismic creep at temperatures much cooler than the onset of crystal plasticity, unless a boundary condition changes. Within this model framework, earthquakes may nucleate when a local increase in strain rate triggers velocity-weakening slip, and we speculate that slip area and event magnitude increase with increasing spacing of strong, topographically derived irregularities in the subduction interface.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Uncontrolled Keywords:	Geodynamics; Natural hazards; Structural geology; Tectonics
Publisher:	Nature Research
ISSN:	1752-0894
Date of First Compliant Deposit:	20 December 2016
Date of Acceptance:	14 November 2016
Last Modified:	06 Nov 2023 23:56
URI:	https://orca.cardiff.ac.uk/id/eprint/97000

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