GNGTS 2017 - 36° Convegno Nazionale

98 GNGTS 2017 S essione 1.1 Luo S., Bo W., Zhu S. and Fu L.; 2014. Ground surface deformation of L’Aquila earthquake revealed by Insar time series . In Proc. XXV FIG Congress, Engaging the Challenges, Enhancing the Relevance, Kuala Lumpur, Malaysia, Vol. 7051, pp. 1-14. Moro M., Saroli M., Stramondo S., Bignami C., Albano M., Falcucci E., Gori S., Doglioni C., Polcari M., Tallini M., Macerola L., Novali F., Costantini M., Malvarosa F., Wegmüller U.; 2017: New insights into earthquake precursors from InSAR , Nature Scientific Reports, 7 , 12035. Petricca P., Barba S., Carminati E., Doglioni C., Riguzzi F.; 2015: Graviquakes in Italy . Tectonophysics, 656 , 202– 214. Towards a fully automatic and modular procedure for generating a high-relolution earthquake catalog of the 2016-17 Central Italy seismic sequence M. Cattaneo 2 , D. Spallarossa 1 , D. Scafidi 1 , S. Marzorati 2 , P. De Gori 2 , C. Chiarabba 2 , L. Chiaraluce 2 , G. Ferretti 1 , M. Segou 3 , B. Baptie 3 , D. Hawthorne 3 , V. Lane 4 , M. Moretti 2 1 DISTAV – Dipartimento di Scienze della Terra, dell’Ambiente e della Vita, Università di Genova, Italy 2 Istituto Nazionale di Geofisica e Vulcanologia, Roma/Ancona, Italy 3 British Geological Survey, Edinburgh, England 4 SEIS-UK, University of Leicester, England Data acquisition. The 2016-17 central Italy sequence activated an about 60-km-long normal-fault system composed by a set of SW-dipping normal fault segments (Chiaraluce et al. , 2017). Following the first mainshock of August 24 (MW 6.0), a very intense seismic activity developed in space and time, and is still active at the time of preparation of this note (September 2017). The hit area was regularly monitored before the sequence onset by the Italian National Seismic Network (RSNC,Amato et al. , 2006) and by additional stations of the RESIICO regional network (Marzorati et al. , 2016). Starting from the day of the first mainshock, the SISMIKO emergency team of INGV began to install a dense array of temporary seismic stations composed by 22 stations deployed complementarily to the permanent ones (Moretti et al. , 2016). After few days, at the beginning of September, colleagues of the British Geological Survey (BGS) and of the School of Geosciences at the University of Edinburgh offered a scientific collaboration consisting of the deployment of additional 24 BB stations. The 10th of September, the seismic network counts 60 station, with a mean inter-distance of 6-8 km, comparable to the earthquakes distribution at depth. This network configuration was kept working until the end of August 2017, producing a final dataset of continuous waveforms, recorded at 155 stations located within 50 km of distance from the epicentral area, of more than 2.5 TB of data. This dataset of continuous recording represents the base for generating a high resolution catalog of earthquakes by means of a fully automatic procedure including modules for event detection, P- and S-waves arrival times, location and magnitude computation. Automatic detection and picking. The whole dataset of continuous recordings was submitted at first to an automatic detection procedure based on a STA/LTA analysis (empirically calibrated for each station as a function of site’s ambient noise, sensor type, etc.) and on a coincident system (empirically calibrated for the network) defining the number of data channels which must be triggering coincidentally within a coincident window in order to declare the start of a potential event. The event detection phase performances has been optimized considering separately sub-networks. The detected events are analysed through an automatic picking procedure. For automatically wave arrival time detecting and locating earthquake an evolution of the RSNI-Picker (Spallarossa et al. , 2014; Scafidi et al. , 2016) has been used. The RSNI-