Allen, R. M.

We evaluate the capability of ElarmS to work as an Early Warning System for the next destructive earthquake in Italy. Potential sources were retrieved from the Database of Individual Seismogenic Sources (DISS; http://www.ingv.it/DISS/) and from the catalogue of historical earthquakes (CPTI04; http://emidius.mi.ingv.it/CPTI/). Based on the geometry of the new Italian Broad-Band Seismic Network, we estimate the "Alert time" for each source from different nucleation points and the size of the shadow zone, the area already affected by S-waves. We present our results for peninsular Italy with a particular attention to the metropolitan areas of Napoli, (Southern Italy) that have been selected as a test site for the SAFER project (http://www.saferproject.net/), plus Roma and Firenze.

The new Italian National Seismic Network (INSN) is a dense network of broadband stations deployed for monitoring Italian seismicity. The network consists of 250 stations with a typical station spacing of !40 km. Earthquake early warning is the rapid detection of an event in progress, assessment of the hazard it poses, and transmission of a warning ahead of any significant ground motion. We explore the potential for using the INSN real-time network for the purpose of earthquake early warning. We run the ElarmS early warning methodology off-line using a data set of more than 200 events with magnitudes between 2.5 and 6.0. A scaling relation for magnitude determination from the dominant period of the first seconds of signal following the P onset is developed from the data set. The standard deviation in the magnitude estimates using this approach is 0.4 magnitude units, and all event magnitude estimates are within !0:75 magnitude units of the true magnitude. Given the existing distribution of seismic stations it takes an average of 10 sec after event initiation before the P wave has been detected at four stations. If we require a detection at four stations before issuing the first alert, then the blind zone, within which no warning would be available, has a radius of !37 km. The ElarmS methodology can provide a warning earlier than this but with a greater uncertainty. An assessment of past damaging earthquakes across Italy shows that applying ElarmS with the existing seismic network could provide warning to population centers in repeats of past events. For example, in a repeat of the 1980 Irpinia earthquake Naples could receive an !15- sec warning. The variations in the size of the blind zone and warning times for different regions can be used as a guide to selecting strategic locations for future station deployments.

We present the test of a simple and rapid methodology for earthquake detection and phase association dedicated to dense and reliable networks of seismic stations. The system is ba- sed on the idea of small subnets of stations each one surrounding the station that produce the first trigger. The goal is to provide a rapid detection of relevant earthquakes and to activate ElarmS but also to prevent misinterpretation of out of the network events or the association of false triggers. We apply this system to the case of the Italian National Seismic Network and to the Italian seismicity.