Designing the expanded microseismic monitoring network for an unstable rock face in Northern Italy

The microseismic monitoring technique is capable of providing important information for revealing the fracture propagation within the rock mass on unstable rock slopes, and thus giving early warning alarms for rockfall hazards. In order to reliably locate microseismic events induced by fracturing, network geometry should be carefully designed. We applied a simplified method to densify a small microseismic network that is currently in operation with five three-component geophones for monitoring an unstable rock face in Northern Italy. In order to calculate the location accuracy, synthetic data affected by random noise were used. The noise level was properly calibrated based on real seismic shots. Considering the constraints on the number of the available channels, 10 additional geophones could provide an acceptable location error within 4-6 m. We also compared the channel performance of the five three-component geophones to explore the preferable orientation of future additional geophones.