Bollettino Sismico Italiano 2011

Abstract

This work illustrates the state of the Italian National Seismic Network (RSNI) and the main characteristics of the seismicity in Italy during 2011. In that year the RSNI located 16,499 events recorded by 359 stations belonging to INGV, and to other local and regional networks connected in real time to the National Earthquake Center in Rome. The apparent minimum magnitude of completeness of the Bollettino Sismico Italiano (BSI) is ML 1.5. The event of maximum magnitude (ML 4.8) was located in Veneto, in the Po Valley. We have identified 46 relevant seismic sequences during 2011. The Montefeltro sequence began in late May and lasted several months, with two events of magnitude ML 4.0. The Pollino sequence is remarkable for its duration: it started in 2009, and repeatedly struck the area, reaching magnitude 5.2 MW on October 25th, 2012; this sequence shows at the beginning of 2011 an increase of seismicity that culminates with the major event of that year (3.6 ML). Analyzing the BSI 2011 we also identified a new area subject to anthropogenic events (quarry blasts), in addition to the 16 areas already identified in previous works. We also consider signals produced by landslides from collapses, widespread in our country along the Alpine and Apennine arcs.