GNGTS 2014 - Atti del 33° Convegno Nazionale

90 GNGTS 2014 S essione 1.1 Tortorici L., Monaco C., Tansi C. and Cocina O.; 1995: Recent and active tectonics in the Calabrian Arc (southern Sicily). �� Tectonophysics, 243 , 37-55. Valensise G. and Pantosti D.; 1992: A 125 Kyr-long geological record of seismic source repetability: in the Messina Straits (southern Italy) and the 1908 earthquake . Terra Nova, 44 : 472-483. Waelbroeck C., Labeyrie L., Michel E., Duplessy J.C., Mcmanus J.F., Lambeck K., Balbon E. and Labracherie M.; 2002: Sea-level and deep water temperature changes derived from benthic foraminifera isotopic records . Quatern. Sci. Rev., 21 : 295–305. Westaway R.; 1993: Quaternary uplift of southern Italy. Journ. of Geophysical Research, 98 : 21741-21772. OPTIMIZING THE ANTELOPE ® PROCEDURES TO LOCATE AUTOMATICALLY THE SEISMIC EVENTS IN NE ITALY L. Moratto, D. Sandron OGS - Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Trieste, Italy Introduction. �� North-eastern Italy, with the nearby regions of Austria, Slovenia and Croatia, is a densely populated area and the seismic hazard is high, with an expected maximum acceleration for an exceedance probability of 10% in 50 years between 0.250 and 0.275 g (Gruppo di Lavoro MPS, 2004); further the Emilia sequence occurred in 2012 evidences the presence of significant seismicity also in the Po plan zone and its effects are felt in all area. The scientific institution deputed for the earthquake monitoring in North-eastern Italy is OGS (the National Institute of Oceanography and Experimental Geophysics), through its Seismological Research Centre (CRS). OGS manages the seismic network that consists of 37 seismic stations and it integrates the regional seismic networks of Friuli Venezia Giulia (FVG hereafter) and Veneto regions, as well as that of Trentino region. The seismological recordings are acquired in real-time and merged in a unique system using the BRTT Antelope ® software (Bragato et al. , 2011a) from Boulder Real-Time Technologies (BRTT), that takes care of the data acquisition, automatic location, data archiving and the alert system via Short Message Service (SMS), email, fax and web. At the same time the Antelope ® system manages the real- time data exchange in the Southern-Alps area with the ‘Zentralanstalt für Meteorologie und Geodynamik’ (ZAMG) in Austria, the ‘Agencija Republike Slovenije za Okolje’ (ARSO) in Slovenia, the ‘University of Trieste’ (UNITS) and the Swiss Seismological Service (SED). The transfrontalier waveforms sharing improves the actual network geometries and, as consequence, the earthquake detection threshold near the borders; the real-time data exchange increases strongly the number of recording stations acquired in the OGS datacenter and nowadays more than 100 stations are used to locate the seismic events. The earthquakes are located in real-time and the related hypocenter coordinates with the magnitude estimations are immediately sent to the regional civil defence headquarters; later the recordings are manually processed off-line for the bulletin production (Priolo et al. , 2005). All locations are also uploaded on the related CRS web pages ( www.crs.inogs.it) . The earthquake page reports location, magnitude and picking data according to the HYPO71 standard ( Lee and Lahr, 1975 ); the analysis on the complete catalogue evidences that the completeness magnitude is equal to 1.5 (Gentili et al. , 2011), the median horizontal and vertical uncertainties are 3.4 km (95% within 11 km) and 4.2 km (95% within 16 km) respectively and the median rms travel time residual is equal to 0.8 s (95% within 1.4 s) (Sandron, 2011). In this study we develop an automatic procedure that detects and locates all earthquakes occurred in north-eastern Italy (NEI area hereafter) evidenced in Fig. 1; we configure the software to recognize and to estimate automatically preliminary locations for the largest number of seismic events, also the weakest ones concerning the microseismicity field. In particular our