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Stability of faults with heterogeneous friction properties and effective normal stress

Luo, Yingdi and Ampuero, Jean-Paul (2018) Stability of faults with heterogeneous friction properties and effective normal stress. Tectonophysics, 733 . pp. 257-272. ISSN 0040-1951. doi:10.1016/j.tecto.2017.11.006.

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Abundant geological, seismological and experimental evidence of the heterogeneous structure of natural faults motivates the theoretical and computational study of the mechanical behavior of heterogeneous frictional fault interfaces. Fault zones are composed of a mixture of materials with contrasting strength, which may affect the spatial variability of seismic coupling, the location of high-frequency radiation and the diversity of slip behavior observed in natural faults. To develop a quantitative understanding of the effect of strength heterogeneity on the mechanical behavior of faults, here we investigate a fault model with spatially variable frictional properties and pore pressure. Conceptually, this model may correspond to two rough surfaces in contact along discrete asperities, the space in between being filled by compressed gouge. The asperities have different permeability than the gouge matrix and may be hydraulically sealed, resulting in different pore pressure. We consider faults governed by rate-and-state friction, with mixtures of velocity-weakening and velocity-strengthening materials and contrasts of effective normal stress. We systematically study the diversity of slip behaviors generated by this model through multi-cycle simulations and linear stability analysis. The fault can be either stable without spontaneous slip transients, or unstable with spontaneous rupture. When the fault is unstable, slip can rupture either part or the entire fault. In some cases the fault alternates between these behaviors throughout multiple cycles. We determine how the fault behavior is controlled by the proportion of velocity-weakening and velocity-strengthening materials, their relative strength and other frictional properties. We also develop, through heuristic approximations, closed-form equations to predict the stability of slip on heterogeneous faults. Our study shows that a fault model with heterogeneous materials and pore pressure contrasts is a viable framework to reproduce the full spectrum of fault behaviors observed in natural faults: from fast earthquakes, to slow transients, to stable sliding. In particular, this model constitutes a building block for models of episodic tremor and slow slip events.

Item Type:Article
Related URLs:
URLURL TypeDescription
Luo, Yingdi0000-0002-1165-6107
Ampuero, Jean-Paul0000-0002-4827-7987
Additional Information:© 2017 Elsevier B.V. Received 16 August 2017, Revised 15 October 2017, Accepted 4 November 2017, Available online 15 November 2017. We acknowledge support from the National Science Foundation awards EAR-1015698 and EAR-1151926 and from the Southern California Earthquake Center (Contribution No. 7946). SCEC is funded by NSF Cooperative Agreement EAR-1033462 and USGS Cooperative Agreement G12AC20038.
Group:Seismological Laboratory
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)UNSPECIFIED
Subject Keywords:Fault heterogeneity; Heterogeneous pore-pressure; Slip instability; Earthquakes; Rate-and-state friction; Linear stability analysis
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center7946
Record Number:CaltechAUTHORS:20171116-095038289
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Official Citation:Yingdi Luo, Jean-Paul Ampuero, Stability of faults with heterogeneous friction properties and effective normal stress, Tectonophysics, Volume 733, 2018, Pages 257-272, ISSN 0040-1951,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:83251
Deposited By: Tony Diaz
Deposited On:16 Nov 2017 18:01
Last Modified:15 Nov 2021 19:56

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