Seismicity in sheared granular matter

TL;DR

This study investigates seismic-like events in sheared granular matter through experiments with a slider on photo-elastic disks, revealing different regimes of crackling and periodicity with distinct statistical laws.

Contribution

It provides new experimental insights into the statistical properties of seismic-like events in granular media under varying driving rates.

Findings

At low driving rates, crackling obeys Omori-Utsu, Bath, and waiting time laws.

Higher driving rates induce periodicity and distinct scaling laws.

Event shapes become asymmetrical in the periodic regime.

Abstract

We report on experiments investigating the dynamics of a slider that is pulled by a spring across a granular medium consisting of a vertical layer of photo-elastic disks. The motion proceeds through a sequence of discrete events, analogous to seismic shocks, in which elastic energy stored in the spring is rapidly released. We measure the statistics of several properties of the individual events: the energy loss in the spring, the duration of the movement, and the temporal profile of the slider motion. We also study certain conditional probabilities and the statistics of mainshock-aftershock sequences. At low driving rates, we observe crackling with Omori-Utsu, Bath, and waiting time laws similar to those observed in seismic dynamics. At higher driving rates, where the sequence of events shows strong periodicity, we observe scaling laws and asymmetrical event shapes that are clearly distinguishable from those in the crackling regime.