Fast automatic strong motion data analysis for Civil Protection purposes: the 2012 Ferrara earthquake example (Northern Italy)

A fast seismic data analysis is essential to provide useful information to Authorities which make decisions immediately after a strong earthquake occurrence. During a strong earthquake, the modern accelerometers are the only instruments which can provide near source high-quality data that are important both for scientific and for civil protection purposes. Automatic and fast techniques have been developed by the University of Trieste for the automatic real-time strong motion data analysis. These techniques have been installed and optimized in the data acquisition centre of the Department of Civil Protection of Italy (DPC) to process the quasi real-time data of the National Accelerometric Network (RAN). RAN counts more than 450 stations covering all the Italian territory. Two local networks, the Friuli Venezia Giulia Accelerometric Network (RAF), located in NE Italy, and the Irpinia Seismic Network (ISNet), contribute their data into the RAN data acquisition system. 148 stations of the integrated RAN triggered the main shock of the Ferrara arc 2012 sequence. The RAN stations recorded the strong motions of the ML 5.9 mainshock, as well as of the major ML 4.1 foreshock and of nearly 35 aftershocks of magnitude ML ¡Ý 4.0. Soon after the mainshock, the DPC installed 15 temporary stations to increase the network coverage in the epicentral area. The performance of the network and of the fast automatic strong motion data analysis during the 2012 Ferrara sequence is analysed. The value of the strong motion parameters calculated by means of the automatic procedure immediately after the events show small differences with respect to the visual inspection procedure. Other aspects related to the seismic source, attenuation of seismic waves, directivity effects and to the comparison between distribution and attenuation of earthquake engineering parameters and observed damage are discussed, highlighting the robustness of the proposed automatic procedure.