Analogies between the cracking noise of ethanol-dampened charcoal and earthquakes

TL;DR

This study investigates the cracking noise of ethanol-dampened charcoal, revealing that seismic laws like Gutenberg-Richter and Omori's law also apply to fracture processes under complex loading conditions similar to natural earthquakes.

Contribution

It demonstrates that fundamental seismic laws are valid in charcoal cracking experiments influenced by ethanol evaporation, highlighting parallels with natural and induced seismicity.

Findings

Seismic laws generally hold in charcoal cracking noise experiments.

Discrepancies include a smaller Gutenberg-Richter exponent and stationary aftershock rates.

Results support the analogy between fracture processes and earthquakes under complex loading.

Abstract

We report on an extensive characterization of the cracking noise produced by charcoal samples when dampened with ethanol. We argue that the evaporation of ethanol causes transient and irregularly distributed internal stresses that promote the fragmentation of the samples and mimic some situations found in mining processes. The results show that, in general, the most fundamental seismic laws ruling earthquakes (Gutenberg-Richter law, unified scaling law for the recurrence times, Omori's law, productivity law and Bath's law) hold under the conditions of the experiment. Some discrepancies were also identified (a smaller exponent in Gutenberg-Richter law, a stationary behavior in the aftershock rates for long times and a double power-law relationship in productivity law) and related to the different loading condition. Our results thus corroborate to elucidate the parallel between seismic laws and fracture experiments caused by a more complex loading condition that also occurs in natural and induced seismicity (such as long-term fluid injection and gas-rock outbursts in mining processes).