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Slip-rate-dependent friction as a universal mechanism for slow slip events

Im, Kyungjae and Saffer, Demian and Marone, Chris and Avouac, Jean-Philippe (2020) Slip-rate-dependent friction as a universal mechanism for slow slip events. Nature Geoscience, 13 . pp. 705-710. ISSN 1752-0894.

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[img] Image (JPEG) (Extended Data Fig. 1: Evolution of peak velocity and stress drop with stability transition) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 2: Comparison of stability transition between laboratory data and simulation results) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 3: Experimental data for velocity dependence of friction parameters) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 4: Influence of simulation mass on earthquake slip rate) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 5: Simple kinematic model for slip propagation) - Supplemental Material
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A growing body of observations worldwide has documented fault slip transients that radiate little or no seismic energy. The mechanisms that govern these slow slip events (SSEs) and their wide range of depths, slip rates, durations, stress drops and recurrence intervals remain poorly known. Here we show that slow slip can be explained by a transition from rate-weakening frictional sliding at low slip rates towards rate-neutral or rate-strengthening behaviour at higher slip rates, as has been observed experimentally. We use numerical simulations to illustrate that this rate-dependent transition quantitatively explains the experimental data for natural fault rocks representative of materials in the source regions of SSEs. With a standard constant-parameter rate-and-state friction law, SSEs arise only near the threshold for slip instability. The inclusion of velocity-dependent friction parameters substantially broadens the range of conditions for slow slip occurrence, and produces a wide range of event characteristics, which include stress drop, duration and recurrence, as observed in nature. Upscaled numerical simulations that incorporate parameters consistent with laboratory measurements can reproduce geodetic observations of repeating SSEs on tectonic faults. We conclude that slip-rate-dependent friction explains the ubiquitous occurrence of SSEs in a broad range of geological environments.

Item Type:Article
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URLURL TypeDescription ReadCube access ItemData ItemData
Im, Kyungjae0000-0003-0057-3119
Saffer, Demian0000-0003-3681-0040
Avouac, Jean-Philippe0000-0002-3060-8442
Additional Information:© 2020 Nature Publishing Group. Received 23 December 2019; Accepted 28 July 2020; Published 07 September 2020. We thank to J. Leeman, S. Michel and A. Gualandi for sharing data. This study was supported by NSF EAR-1821853 to J.-P.A., NSF EAR-1616664 and OCE-1334436 to D.S. and NSF EAR-1763305 and EAR-1520760 to C.M. Data availability: GPS data for Hikurangi and Ryuku are publicly available at the Nevada Geodetic Laboratory ( and Mexico GPS data35 and Cascadia inversion data33 are available at the Caltech data repository47 ( Source data are provided with this paper. Code availability: Simulation codes are available at Caltech data repository ( Author Contributions: K.I. led the numerical modelling effort and writing of the manuscript. All the authors contributed to the interpretation of modelling results and writing the manuscript. D.S. and C.M. initiated the study and contributed to experimental data analysis. K.I. and J.-P.A. led the GPS data analysis. The authors declare no competing interests.
Group:Seismological Laboratory
Funding AgencyGrant Number
Subject Keywords:Seismology; Tectonics
Record Number:CaltechAUTHORS:20200722-143843550
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Official Citation:Im, K., Saffer, D., Marone, C. et al. Slip-rate-dependent friction as a universal mechanism for slow slip events. Nat. Geosci. 13, 705–710 (2020).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104516
Deposited By: George Porter
Deposited On:08 Sep 2020 19:37
Last Modified:01 Oct 2020 17:07

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