A microseismic-based procedure for the detection of rock slope instabilities

• Rock fracturing is accompanied by generation and transmission of elastic waves.
• Microseismic monitoring systems allow to detect and record elastic waves.
• If signals are caused by a common rupture mechanism, they are similar in waveform.
• Location of similar signals contributes in identifying potentially unstable areas.

The accumulation and spatial location of damage can lead to the progressive formation of macroscale discontinuities and the possible collapse of portions of rock slopes. Since rock fracturing is accompanied by the generation and transmission of elastic waves that travel through the affected material, an analysis procedure that is able to interpret data, recorded by means of a microseismic monitoring system, has been developed. The procedure is made up of three main parts: the identification and grouping of similar events, the hypocenter location of grouped events and the cross-analysis of the spatial distribution of the source events with the structural setting of the investigated area.The application of this methodology to a dataset recorded by a monitoring system installed on the Matterhorn mountain has pointed out that this approach can contribute to recognizing areas subjected to a common rupture mechanism, which can concern one single fracture or a set of neighboring fractures. If signals that are generated over time from a certain area have a waveform with similar characteristics, the rupture mechanism that causes the signals is the same. At this regard, a good knowledge of the local structural setting of the slope and of the characteristics of some documented rockfall events can contribute in supporting the above statement and help focus on areas where failures are kinematically possible.