A framework for temporal and spatial rockfall early warning using micro-seismic monitoring
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Liang Feng I Emanuele Intrieri I Veronica Pazzi I Giovanni Gigli I Grazia Tucci
A framework for temporal and spatial rockfall early warning using micro-seismic monitoring
Abstract Rockfall risk is usually characterized by a high frequency of occurrence, difficulty in prediction (given high velocity, lack of noticeable forerunners, abrupt collapse, and complex mechanism), and a relatively high potential vulnerability, especially against people and communication routes. Considering that larger rockfalls and rockslides are generally anticipated by an increased occurrence of events, in this study, a framework based on microseismic monitoring is introduced for a temporal and spatial rockfall early warning. This approach is realized through the detection, classification, and localization of all the rockfalls recorded during a 6-month-long microseismic monitoring performed in a limestone quarry in central Italy. Then, in order to provide a temporal warning, an observable quantity of accumulated energy, associated to the rockfall rolling and bouncing and function of the number and volume of events in a certain time window, has been defined. This concept is based on the material failure method developed by Fukuzono-Voight. As soon as the first predicted time of failure and relative warning time are declared, all the rockfalls occurred in a previous time window can be located in a topographic map to find the rockfall susceptible area and thus to complement the warning with spatial information. This methodology has been successfully validated in an ex post analysis performed in the aforementioned quarry, where a large rockfall was forecasted with a lead time of 3 min. This framework provides a novel way for rockfall spatiotemporal early warning, and it could be helpful for activating traffic lights and closing mountain roads or other transportation lines using the knowledge of the time and location of a failure. Since this approach is not based on the detection of the triggering events (like for early warnings based on rainfall thresholds), it can be used also for earthquake-induced failures. Keywords Rockfall . Microseismic monitoring . Rockfall susceptibility . Landslide early warning . Time series analysis Introduction The economic and population development, increasing access and construction in mountainous areas, bring people and infrastructures to a higher exposure to slope hazards (Dammeier et al. 2011). Reliable slope hazard prediction on brittle rock is still a hard task, due to the lack of noticeable forerunners preceding abrupt failures as well as the complex mechanisms not fully understood yet (Carlà et al. 2017). Nowadays, there are several ways to perform landslide early warning. One way is to monitor displacements (Iovine et al. 2006; Blikra 2012; Kristensen et al. 2013; Lombardi et al. 2017; Intrieri et al. 2019), which is a direct indicator of slope instability. Although future developments in the exploitation of interferometric satellites might lead to a bloom of regional scale early warning systems (Raspin
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