Acoustic Emissions and Microseismicity in Granular Slopes Prior to Failure and Flow‐Like Motion: The Potential for Early Warning

Rain‐triggered landslides in loosely packed granular deposits are highly hazardous because of their sudden failure, flow‐like motion, and high mobility. Predicting their initiation and establishing monitoring and early‐warning strategies based on the actual mechanisms of failure, rather than on statistical‐empirical relations, can be challenging. Experiments on artificial granular slopes revealed a systematic instability‐triggering process entailing the internal erosion and seepage‐driven transport of small grains. This rearrangement of matter generates acoustic signals and microseismicity detectable prior to any pore water pressures spikes or macroscopic deformations, which are common proxies for slope stability monitoring. Acoustic emissions are more pronounced in loose assemblies, while they are much weaker in densely packed mixtures, which will not exhibit fluid‐like motion. Acoustic sensors and accelerometers in support to monitoring networks for flow‐like landslides can improve our early warning capabilities, as long as their good performance is confirmed in real‐scale applications.