The Irpinia Seismic Network (ISN): a new Monitoring Infrastructure for Seismic Alert Management in Campania Region, Southern Italy

The Irpinia Seismic Network is an high dynamics, high density seismographic network under development in the Southern Apenninic chain. It is deployed in the area stroken by several destructive earthquakes during last centuries. In its final configuration the network will consist of more than fourty high dynamic seismic stations subdivided in physical subnetworks inter-connected by a robust data transmission system. The system is being designed with two primary targets: -Monitoring and analysis of background seismic activity produced by the active fault system which is the cause for large earthquakes in the past, included the 1980, Irpinia earthquake (Ms=6.9) - Development and experimentation of a prototype system for seismic early and post-event warning to be used for protecting public infrastructures and buildings of strategic relevance of the Regione Campania The seismic network will be completed in two stages: 1 - Deployment of 30 seismic stations along the Campania-Lucania Apenninic chain (to date almost completed) 2 - Setting up radio communication system for data transmission. Installation of 12 additional seismic stations (end of year 2006) To ensure an high dynamic recording range each site is equipped with two type of sensors: 30 force-balance accelerometer (model Guralp CMG5-T) and a velocimeter. In particular, 25 sites with short period three components instrument (model Geotech S13-J) and 5 with broad-band sensor (Nanometrics Trillium, with frequency response in the 0.033-50 Hz band). The used data logger is the Osiris-6 model produced by Agecodagis whose main features are: six channels, O/N 24 bit A/D converter, ARM processor with embedded Linux and open source software, two PCMCIA slots (used for two 5GB microdrive or one disk and wi-fi card), Ethernet, wi-fi and serial communication, low power cosumption (~1 W). Power is ensured by two 120 W solar panels and two 130 Ah gel batteries. Each recording site is equipped with a control/alarm system through a Programmable Logic Controller-GSM modem connected to several ambient sensors (forcing, battery control, fire, temperature) to remotely control the site status. Data are locally stored on the 5GB disk and continuously transmitted by the SeedLink protocol through a point-to-point wireless LAN bridge to interconnection nodes (Local Control Center, LCC). At LCC sites an Earthworm system runs on a dedicated computer to manage the data stream acquired by stations directly connected to LCC. The real time analysis system performs event detection and location based on triggers coming from data loggers and parametric information provided by the other LCCs. At present, data transmission among LCC is performed via commercial ADSL. Once an event is detected and located, the system performs automatic magnitude and focal mechanism estimation. The results of this analysis are used to build a local event Data Base (DB) and, at the same time, they are sent to other LCC and to the network operating room located in Naples (RISSC). At RISSC center the network data are managed by a system gathering parametric data from all the LCC and performing real time analysis based on which it is decided whether or not issuing a seismic alert. Future plans for network operation involve the installation of additional 12 stations, and the upgrading of data transmission system to a proprietary radio link with SDH technology. The project is financial supported by the Campania Regional Department of Civil Protection.