Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

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


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.

This is a preview of subscription content

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Conditions for episodic slow slip.
Fig. 2: Vpeak and normalized stress drop as a function of κ.
Fig. 3: Characteristics of stick–slip events as a function of depth for a generic subduction megathrust.
Fig. 4: Comparison with observed SSEs.

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 repository47 (


  1. 1.

    Obara, K., Hirose, H., Yamamizu, F. & Yamamizu, K. Episodic slow slip events accompanied by non-volcanic tremors in southwest Japan subduction zone. Geophys. Res. Lett. 31, L23602 (2004).

    Article  Google Scholar 

  2. 2.

    Dragert, H., Wang, K. & James, S. T. A silent slip event on the deeper Cascadia subduction interface. Science 292, 1525–1528 (2001).

    Article  Google Scholar 

  3. 3.

    Kostoglodov, V. et al. A large silent earthquake in the Guerrero seismic gap, Mexico. Geophys. Res. Lett. 30, 1807 (2003).

    Article  Google Scholar 

  4. 4.

    Kano, M. et al. Development of a slow earthquake database. Seismol. Res. Lett. 89, 1566–1575 (2018).

    Article  Google Scholar 

  5. 5.

    Jiang, Y. et al. Slow slip events in Costa Rica detected by continuous GPS observations, 2002–2011. Geochem. Geophys. Geosyst. 13 (2012).

  6. 6.

    Wallace, L. M. et al. Slow slip near the trench at the Hikurangi subduction zone, New Zealand. Science 352, 701–704 (2016).

    Article  Google Scholar 

  7. 7.

    Tymofyeyeva, E. et al. Slow slip event on the southern San Andreas fault triggered by the 2017 Mw8.2 Chiapas (Mexico) earthquake. J. Geophys. Res Solid Earth 124, 9956–9975 (2019).

    Article  Google Scholar 

  8. 8.

    Rousset, B. et al. An aseismic slip transient on the North Anatolian Fault. Geophys. Res. Lett. 43, 3254–3262 (2016).

    Article  Google Scholar 

  9. 9.

    Hawthorne, J. C. & Rubin, A. M. Tidal modulation of slow slip in Cascadia. J. Geophys. Res. Solid Earth 115, (2010).

  10. 10.

    Kodaira, S. et al. High pore fluid pressure may cause silent slip in the Nankai Trough. Science 304, 1295–1298 (2004).

    Article  Google Scholar 

  11. 11.

    Gao, X. & Wang, K. L. Rheological separation of the megathrust seismogenic zone and episodic tremor and slip. Nature 543, 416–419 (2017).

    Article  Google Scholar 

  12. 12.

    Liu, Y. J. & Rice, J.R. Aseismic slip transients emerge spontaneously in three-dimensional rate and state modeling of subduction earthquake sequences. J. Geophys. Res. 110 (2005).

  13. 13.

    Rubin, A. M. Episodic slow slip events and rate-and-state friction. J. Geophys. Res. Solid Earth 113, B11414 (2008).

    Article  Google Scholar 

  14. 14.

    Marone, C. Laboratory-derived friction laws and their application to seismic faulting. Annu. Rev. Earth Planet. Sci. 26, 643–696 (1998).

    Article  Google Scholar 

  15. 15.

    Scuderi, M. M., Collettini, C., Viti, C., Tinti, E. & Marone, C. Evolution of shear fabric in granular fault gouge from stable sliding to stick slip and implications for fault slip mode. Geology 45, 731–734 (2017).

    Google Scholar 

  16. 16.

    Leeman, J. R., Marone, C. & Saffer, D. M. Frictional mechanics of slow earthquakes. J. Geophys. Res. Solid Earth 123, 7931–7949 (2018).

    Article  Google Scholar 

  17. 17.

    Leeman, J. R., Saffer, D. M., Scuderi, M. M. & Marone, C. Laboratory observations of slow earthquakes and the spectrum of tectonic fault slip modes. Nat. Commun. 7 (2016).

  18. 18.

    Baumberger, T., Heslot, F. & Perrin, B. Crossover from creep to inertial motion in friction dynamics. Nature 367, 544–546 (1994).

    Article  Google Scholar 

  19. 19.

    Mitchell, E. K., Fialko, Y. & Brown, K. M. Frictional properties of gabbro at conditions corresponding to slow slip events in subduction zones. Geochem. Geophys. Geosystems 16, 4006–4020 (2015).

    Article  Google Scholar 

  20. 20.

    Segall, P., Rubin, A. M., Bradley, A. M. & Rice, J. R. Dilatant strengthening as a mechanism for slow slip events. J. Geophys. Res. Solid Earth 115 (2010).

  21. 21.

    Skarbek, R. M., Rempel, A. W. & Schmidt, D. A. Geologic heterogeneity can produce aseismic slip transients. Geophys. Res. Lett. 39 (2012).

  22. 22.

    Shibazaki, B. & Shimamoto, T. Modelling of short-interval silent slip events in deeper subduction interfaces considering the frictional properties at the unstable-stable transition regime. Geophys. J. Int. 171, 191–205 (2007).

    Article  Google Scholar 

  23. 23.

    Kaproth, B. M. & Marone, C. Slow earthquakes, preseismic velocity changes, and the origin of slow frictional stick-slip. Science 341, 1229–1232 (2013).

    Article  Google Scholar 

  24. 24.

    Rubin, A. M. Designer friction laws for bimodal slow slip propagation speeds. Geochem. Geophys. Geosyst. 12 (2011).

  25. 25.

    Rice, J. R. & Ruina, A. L. Stability of steady frictional slipping. J. Appl. Mech. Trans. ASME 50, 343–349 (1983).

    Article  Google Scholar 

  26. 26.

    Ikari, M. J., Saffer, D. M. & Marone, C. Frictional and hydrologic properties of clay-rich fault gouge. J. Geophys. Res. Solid Earth 114 (2009).

  27. 27.

    Ikari, M. J. & Saffer, D. M. Comparison of frictional strength and velocity dependence between fault zones in the Nankai accretionary complex. Geochem. Geophys. Geosyst. 12 (2011).

  28. 28.

    Rabinowitz, H. S. et al. Frictional behavior of input sediments to the Hikurangi trench, New Zealand. Geochem. Geophys. Geosyst. 19, 2973–2990 (2018).

    Article  Google Scholar 

  29. 29.

    Mair, K. & Marone, C. Friction of simulated fault gouge for a wide range of velocities and normal stresses. J. Geophys. Res. Solid Earth 104, 28899–28914 (1999).

    Article  Google Scholar 

  30. 30.

    Saffer, D. M. & Marone, C. Comparison of smectite- and illite-rich gouge frictional properties: application to the updip limit of the seismogenic zone along subduction megathrusts. Earth Planet. Sci. Lett. 215, 219–235 (2003).

    Article  Google Scholar 

  31. 31.

    Scholz, C. H. Earthquakes and friction laws. Nature 391, 37–42 (1998).

    Article  Google Scholar 

  32. 32.

    Saffer, D. M. & Tobin, H. J. Hydrogeology and mechanics of subduction zone forearcs: fluid flow and pore pressure. Annu. Rev. Earth Planet. Sci. 39, 157–186 (2011).

    Article  Google Scholar 

  33. 33.

    Michel, S., Gualandi, A. & Avouac, J.-P. Similar scaling laws for earthquakes and Cascadia slow-slip events. Nature 574, 522–526 (2019).

    Article  Google Scholar 

  34. 34.

    Kano, M., Fukuda, J., Miyazaki, S. & Nakamura, M. Spatiotemporal evolution of recurrent slow slip events along the southern Ryukyu subduction Zone, Japan, from 2010 to 2013. J. Geophys. Res. Solid Earth 123, 7090–7107 (2018).

    Google Scholar 

  35. 35.

    Gualandi, A., Perfettini, H., Radiguet, M., Cotte, N. & Kostoglodov, V. GPS deformation related to the Mw 7.3, 2014, Papanoa earthquake (Mexico) reveals the aseismic behavior of the Guerrero seismic gap. Geophys. Res. Lett. 44, 6039–6047 (2017).

    Article  Google Scholar 

  36. 36.

    Radiguet, M. et al. Slow slip events and strain accumulation in the Guerrero gap, Mexico. J. Geophys. Res. Solid Earth 117 (2012).

  37. 37.

    Heki, K. & Kataoka, T. On the biannually repeating slow-slip events at the Ryukyu Trench, southwestern Japan. J. Geophys. Res. Solid Earth 113 (2008).

  38. 38.

    Ruina, A. Slip instability and state variable friction laws. J. Geophys. Res. 88, 10359–10370 (1983).

    Article  Google Scholar 

  39. 39.

    Ampuero, J. P. & Rubin, A. M. Earthquake nucleation on rate and state faults–aging and slip laws. J. Geophys. Res. 110, 1–24 (2008).

    Google Scholar 

  40. 40.

    Bhattacharya, P., Rubin, A. M., Bayart, E., Savage, H. M. & Marone, C. Critical evaluation of state evolution laws in rate and state friction: fitting large velocity steps in simulated fault gouge with time-, slip- and stress-dependent constitutive laws. J. Geophys. Res. Solid Earth 120 (2015).

  41. 41.

    Im, K., Marone, C. & Elsworth, D. The transition from steady frictional sliding to inertia-dominated instability with rate and state friction. J. Mech. Phys. Solids (2019).

  42. 42.

    Dieterich, J. H. Earthquake nucleation on faults with rate and state dependent strength. Tectonophysics 211, 115–134 (1992).

    Article  Google Scholar 

  43. 43.

    Ikari, M. J., Marone, C., Saffer, D. M. & Kopf, A. J. Slip weakening as a mechanism for slow earthquakes. Nat. Geosci. 6, 468–472 (2013).

    Article  Google Scholar 

  44. 44.

    Saffer, D. M. & Wallace, L. M. The frictional, hydrologic, metamorphic and thermal habitat of shallow slow earthquakes. Nat. Geosci. 8, 594–600 (2015).

    Article  Google Scholar 

  45. 45.

    Ikari, M. J. & Kopf, A. J. Seismic potential of weak, near-surface faults revealed at plate tectonic slip rates. Sci. Adv. 3, e1701269 (2017).

    Article  Google Scholar 

  46. 46.

    Im, K., Elsworth, D., Marone, C. & Leeman, J. The impact of frictional healing on stick–slip recurrence interval and stress drop: implications for earthquake scaling. J. Geophys. Res. Solid Earth 122, 10102–10117 (2017).

    Article  Google Scholar 

  47. 47.

    Im, K. Slip Rate-Dependent Friction as a Universal Mechanism for Slow Slip Events (Version 1.0) (Data Set) (CaltechDATA, 2020);

  48. 48.

    Okada, Y. Surface deformation due to shear and tensile faults in a half-space. Bull. Seismol. Soc. Am. 75, 1135–1154 (1985).

    Google Scholar 

Download references


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.

Author information




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.

Corresponding author

Correspondence to Kyungjae Im.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Primary Handling Editor: Stefan Lachowycz.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Evolution of peak velocity and stress drop with stability transition.

a, e, constant parameter, b, f, velocity dependent Dc, c, g, velocity dependent a, d, h, velocity dependent Dc and a cases. Panels a and d are identical to Figs. 1a and 1b, respectively. We used, Dc0 = 10 µm, SDc = 60 µm and VDc = 100 µm/s for velocity dependent Dc and a0 = 0.005, Sa = 0.0003, Va = 100 µm/s for velocity dependent a simulations.

Extended Data Fig. 2 Comparison of stability transition between laboratory data and simulation results.

Friction drop as a function of normal stress and loading velocity for a, laboratory experiments16, and b-e, simulations with b: constant parameters, c: velocity dependent Dc, d: velocity dependent a, and e: velocity dependence of both a and Dc. Simulation results in b-e are identical to Extended Data Fig. 1e–h, but re-sized to match the laboratory results of Panel a.

Extended Data Fig. 3 Experimental data for velocity dependence of friction parameters.

a, Experimental data showing Dc as a function of sliding velocity for quartz gouge29. Blue circles are measurements and solid line represents the velocity dependence we used in our laboratory scale simulations (Figs. 1 and 2). For tectonic fault zone simulations, we used identical SDc, but with Dc0 = 100 µm and VDc = 10−9 m/s. b, Compiled experimental data for a-b on tectonic fault zone materials27. Dashed line denotes the trend line of all measurement. We used the slop of the trendline (0.0013 per decade) for upscaled (Fig. 3) simulations.

Extended Data Fig. 4 Influence of simulation mass on earthquake slip rate.

Here we only considered constant parameter RSF cases, with high pore pressure. Red squares (M = 600000 kg/m2) are identical to main text Fig. 3 gray squares (Constant parameters high pore pressure). Blue and black squares show cases with one order of magnitude smaller and larger mass, respectively. Panel c shows that the peak velocity is dependent on the mass. However, even we assume significantly larger mass, stick slip abruptly evolves to fast rupture (Vpeak > 1 cm/s) at the transition.

Extended Data Fig. 5 Simple kinematic model for slip propagation.

a, Model illustration. We assume 200 km × 63 km slipping patch (light yellow) embedded in a half space with its lower edge at a depth of 26 km. For displacement of each patch, we impose the time evolution of slip derived from the spring-slider model adjusted to the Guerrero example (Fig. 4d). We considered three cases for slip propagation along the strike direction at: (i) 1 km/day, (ii) 5 km/day, and (iii) a case with simultaneous slip in the entire patch. Panel b, shows an example of slip propagation for the 1 km/day case. The fault slip is converted to surface deformation using an elastic dislocation (Okada) model48 and the normalized displacements are plotted in panels c&d, for comparison with the observed Guerrero gap GPS timeseries. The result shows that the case with a propagation rate of 5 km/day (red) is nearly indistinguishable from the case of simultaneous slip (equivalent to an infinitely fast propagation). The case with 1 km/day (blue) which is at the lower end of the typical rate of propagation of SSEs, is also only slightly altered by the effect of the propagation.

Source data

Source Data Fig. 1

Data points for Fig. 1.

Source Data Fig. 2

Data points for Fig. 2.

Source Data Fig. 3

Data points for Fig. 3.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

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).

Download citation

Further reading


Quick links