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The predictable chaos of slow earthquakes

Gualandi, A. and Avouac, J.-P. and Michel, S. and Faranda, D. (2020) The predictable chaos of slow earthquakes. Science Advances, 6 (27). Art. No. eaaz5548. ISSN 2375-2548. doi:10.1126/sciadv.aaz5548.

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Slow earthquakes, like regular earthquakes, result from unstable frictional slip. They produce little slip and can therefore repeat frequently. We assess their predictability using the slip history of the Cascadia subduction between 2007 and 2017, during which slow earthquakes have repeatedly ruptured multiple segments. We characterize the system dynamics using embedding theory and extreme value theory. The analysis reveals a low-dimensional (<5) nonlinear chaotic system rather than a stochastic system. We calculate properties of the underlying attractor like its correlation and instantaneous dimension, instantaneous persistence, and metric entropy. We infer that the system has a predictability horizon of the order of days weeks. For the better resolved segments, the onset of large slip events can be correctly forecasted by high values of the instantaneous dimension. Longer-term deterministic prediction seems intrinsically impossible. Regular earthquakes might similarly be predictable but with a limited predictable horizon of the order of their durations.

Item Type:Article
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URLURL TypeDescription Materials
Gualandi, A.0000-0002-3100-8932
Avouac, J.-P.0000-0002-3060-8442
Michel, S.0000-0001-7878-6603
Additional Information:© 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). Submitted 18 September 2019; Accepted 19 May 2020; Published 1 July 2020. We thank K. V. Hodges, M. Ritzwoller, M. Shirzaei, and an anonymous reviewer for comments that helped improve the manuscript. Funding: This study was partially supported by the National Science Foundation through award EAR-1821853. A.G. presented the results of this work at various conferences thanks to an appointment with the NASA Postdoctoral Program at the Jet Propulsion Laboratory, California Institute of Technology, administered by the Universities Space Research Association under contract with NASA, in collaboration with the Agenzia Spaziale Italiana (ASI). S.M. is currently supported by a postdoc fellowship from the French Centre National d’Études Spatiales (CNES). The calculations were performed using MATLAB. For the ET calculations, we have used and modified scripts developed by M. Kizilkaya (function cao_deneme.m), A. Leontitsis (Cahotic Systems Toolbox), and C. Gias (function phaseran.m), all available through the MathWorks portal. Author contributions: A.G. conceived of the presented idea and performed the calculations. A.G. wrote the manuscript with support from J.-P.A. and feedback from S.M. and D.F. S.M. provided help with the data. D.F. supervised the application of EVT. All authors contributed to the discussion and interpretation of the results. Competing interests: The authors declare that they have no competing interests. Data and materials availability: The slip model in (20), which is used as input in this study is available at All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.
Group:Seismological Laboratory
Funding AgencyGrant Number
NASA Postdoctoral ProgramUNSPECIFIED
Agenzia Spaziale Italiana (ASI)UNSPECIFIED
Centre National d’Études Spatiales (CNES)UNSPECIFIED
Issue or Number:27
Record Number:CaltechAUTHORS:20200702-084851713
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Official Citation:A. Gualandi, J.-P. Avouac, S. Michel, D. Faranda, The predictable chaos of slow earthquakes. Sci. Adv. 6, eaaz5548 (2020); doi: 10.1126/sciadv.aaz5548
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104202
Deposited By: Tony Diaz
Deposited On:02 Jul 2020 16:01
Last Modified:16 Nov 2021 18:29

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