Dilation of a shear granular model experiment of earthquake to serve as a possible precursor for catastrophic events

Abstract:

Earthquake forecast has long been an objective for geoscience, resisting scientific efforts for more than a century. This difficulty stems in part from the large spectrum of time and energy scales, a feature required of physics-earthquake analogies [1]. It is now widely accepted that any progress in prediction will come not from any single observable, but in the form of a probabilistic combination (either analytical or based on recent machine-learning progress [2]) of many signals and measurements. The search for precursory signals had lead to a wide variety of candidates, such as slow-slip events [3] or low-frequency changes [4]. New precursors can be searched either in real-world data, or through model experiment – we focus on the later approach.
We present a granular shear experiment in a cylindrical couette geometry [1] which creates artificial quakes in the form of acoustic burst or mechanical energy release. This system has been shown to exhibit quantitative agreement to several key statistical features of earthquakes (Gutenberg-Richter & Omori law, waiting-time distribution [5],...). Additionally, the dilation of the granular medium is monitored during an experimental. This dilation increases on average prior to large events [6]. Furthermore, we show the link between average dilation increase and upcoming events hold for several magnitudes.

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[3] T.A Brzinsky, K. Daniels : Sounds of Failure: Passive Acoustic Measurements of Excited Vibrational Modes, PRL 120, 218003 (2018)

[4] Bryan M. Kaproth, C. Marone : Slow Earthquakes, Preseismic Velocity Changes, and the Origin of Slow Frictional Stick-Slip, Science 341, 1229-1232 (2013)

[5] A Corral : Long-term clustering, scaling, and universality in the temporal occurrence of earthquakes, PRL 92, 108501 (2004)

[6] V. Levy dit Vehel, F. Dubourg, L. Vanel, K. J. Måløy, & O.Ramos : Evolution of the distance between plates in an experimental granular fault. Implications for earthquake forecast, RNL 2018 proceedings (2018)