Performances of Two Automatic Earthquake Location Systems in the Northeastern Italy

In this poster, the new Antelope earthquake location system performances are analyzed and compared with the ones of the already existing FAAS location system. Antelope is used in the framework of the EU Interreg IIIA project started in 2002 “Trans-national seismological networks in the South-Eastern Alps” and involves Italy, Austria and Slovenia: among the scopes of the projects, there is the improving of network geometry for lowering earthquake detection threshold near the borders, by collecting data from several seismic networks in the area. FAAS is the Friuli Automatic Alert System and uses data from the Short-period Seismometric Network of Northeastern Italy (NEI). It monitors the region between Lake Garda on the West and the Italian/Slovenian border on the East as well as a limited portion of Western Slovenia and Southern Austria. It has been active at Centro di Ricerche Sismologiche (CRS), a department of the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), since 1996. It recognizes local earthquakes, performs P and S picking, locates earthquakes and estimates their magnitudes. In addition, FAAS establishes the level of alert for civil protection authorities and seismological institutions. Automatic locations are also reported on the CRS web page (http://www.crs.inogs.it). In this poster, the results of the two automatic location systems are compared with the set of manual relocations of the NEI network bulletin (OGS database). The analysis on the location and picking precision is performed on the common data from the end of 2005: in particular we compute the variance of the differences between the 3 location and picking data sets, inferring the precision of each data set. In addition, the magnitude of completeness is estimated independently for each data set, depending on the area analyzed.