272 Seismic Monitoring of a Rockslide: The Torgiovannetto Quarry (Central Apennines, Italy) A. Lotti, G. Saccorotti, A. Fiaschi, L. Matassoni, G. Gigli, V. Pazzi, and N. Casagli Abstract A small-scale seismic network was deployed in the Torgiovannetto quarry (Central Apennines, Italy) from December 2012 to July 2013 to evaluate the possibility of improving the early-warning monitoring network of a rockslide by means of seismic observations. Four seismometers, acquiring data in continuous mode, were set up inside and at the edge of the quarry, with an average inter-station distance of about 100 m. The entire data set (7 months of recording) was analyzed through three different procedures: an STA/LTA (short-time-average /long-time-average) trigger, HVSR (Horizontal to Vertical Spectral Ratio and NCF (Noise- Correlation Function). The data analysis is still in progress. The preliminary data processing related to the identification and classification of recorded signals shows promising results but further refinements of the adopted algorithms are necessary in order to make this technique an helpful early warning tool. Extensive comparison and cross-analysis with parameters independently recorded by the other instruments of the monitoring network are necessary to reach the goals of the study. Keywords HVSR Á Noise-correlation function Á Early warning Á Rockslide monitoring 272.1 Introduction Landslides are a frequent and widespread geomorphological phenomenon that represent a severe threat to both people and facilities. Italy is one of the European countries most prone to landslides risk. Slope failure of rock masses rep- resents an interesting case study for verifying the ability of passive seismic monitoring in order to detect: (a) signals related to micro-cracking; (b) signals related to rock blocks detachment and fall from the slope useful to reconstruct their associated trajectory; (c) possible variations in the elastic parameters of the rock body related to changes in pore-fluid pressure, consolidation, and micro-fracturing, which could forerun failure. The possibility of measuring such changes would thus constitute a significant improvement in our ability to forecast surface rock failure, and to mitigate the associated hazard. In this study, we describe a pilot experi- ment aimed at verifying the performance of a small-scale seismic network as a part of an early-warning system dedi- cated to an unstable rock mass monitoring. The test site is a dismissed limestone quarry located nearby the town of Assisi (Central Apennines, Italy) where a first rockfall and a subsequent reactivation occurred in 2003 (linked to the opening of the main fracture that we supposed to happen consequently to the 1997 earthquake) and in 2005 respec- tively (Fig. 272.1). In order to verify the performances of the detection and localization employed algorithm, we per- formed man-induced rock falls, then filming the blocks’ A. Lotti (&) Á G. Gigli Á V. Pazzi Á N. Casagli Dipartimento di Scienze della Terra, Università di Firenze, Via La Pira 4, 50121 Florence, Italy e-mail: alessia.lotti.17@gmail.com V. Pazzi e-mail: veronica.pazzi@unifi.it G. Saccorotti Istituto Nazionale di Geofisica e Vulcanologia, Pisa, Italy G. Saccorotti Á A. Fiaschi Á L. Matassoni Fondazione Prato Ricerche, Prato, Italy G. Lollino et al. (eds.), Engineering Geology for Society and Territory – Volume 2, DOI: 10.1007/978-3-319-09057-3_272, © Springer International Publishing Switzerland 2015 1537