RAIS: a real time strong-motion network in northern Italy

When compared to more seismically active regions, damaging earthquakes occur only occasionally in the central part of northern Italy. Nevertheless, the lack of a dense strong-motion network in this area was highlighted by the occurrence of the November 24, 2004, ML 5.2, Salo earthquake. In 2006, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) section of Milano-Pavia began the installation of new strong-motion stations in central-northern Italy. At present, the Strong-Motion Network of Northern Italy (RAIS; Rete Accelerometrica Italia Settentrionale) includes 22 stations with an average inter-distance of about 20 km. All of the stations are equipped with Kinemetrics Episensor FBA ES-T sensors coupled with 24-bit digital recorders. Starting from 2009, 14 strong-motion stations have been sending data to the INGV acquisition center in Milan, in real time using TCP/IP over wi-fi links. Another eight stations still work in dial-up mode and send data through GSM modems. The real-time connections allow the use of strong-motion data recorded by RAIS for the generation of shake maps for Italy, the implementation of which represents one of the main tasks of the last agreement between INGV and the Italian Civil Protection Department. The RAIS data is stored directly at the INGV section of Milano-Pavia, which was realized using the MiniSEED format: the data management and exchange are carried out by the SeisComP package with the SeedLink protocol. Metadata dissemination is achieved through the website http://rais.mi.ingv.it, where the strong-motion parameters related to each recorded and processed waveform are made available.