Seismic monitoring of the gravity-induced deformation involving the Peschiera Spring slope (Italy) for the management of a main infrastructure

The Peschiera Spring slope (Central Apennines, Italy), which hosts the tunnels of the main drainage plant of Rome aqueducts, is involved in a gravity-induced slope deformation. An average aquifer discharge of about 18 m3/s is responsible for an intense limestone dissolution corresponding to the main kinematic elements that dislodge the jointed rock mass. Since 2008 a seismometric network was installed within the tunnels of the drainage plant for detecting local underground instabilities consisting of failures and collapses. About 1000 signals due to instabilities were recorded up to now. A control index (CI), based on both the frequency of occurrence and the cumulative energy of the recorded local instabilities was tested for providing three levels of alert. During the 2014 a total of 32 collapse crises were recorded, that caused several “emergency” states of the plant.