GNGTS 2018 - 37° Convegno Nazionale

110 GNGTS 2018 S essione 1.1 SEISMIC ATTRIBUTES IN SEISMOTECTONIC RESEARCH: AN APPLICATION TO THE MW=6.5 EARTHQUAKE OF 30 OCTOBER 2016 (NORCIA, CENTRAL ITALY) M. Ercoli 1 , E. Forte 2 , M. Porreca 1 , M.R. Barchi 1 , C. Pauselli 1 , G. Minelli 1 1 Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Italy (CRUST Centro inteRUniversitario per l’analisi SismoTettonica tridimensionale con applicazioni territoriali) 2 Dipartimento di Matematica e Geoscienze, Università degli Studi di Trieste, Italy Introduction. In 2016-2017 a long and complex seismic sequence struck Central Italy. It encompasses one of the strongest events (30th October 2016, Mw = 6.5) recorded in the last decades in the Italian Peninsula. A region of about 80 km, elongated in NNW-SSE direction from Visso to Campotosto was interested by the sequence (Chiaraluce et al. , 2017). Several sectors of a long NNW-SSE fault system activated, characterized by prevalent WSW-dipping, high-angle normal faults. However, the geological structure of the area is particularly complex and still debated. Despite a huge amount of data recorded by the geoscientists at the surface, geophysical and geological deep data are very limited and logistically complex to collect in this study area. For this reason, a series of 2D vintage seismic reflection lines, collected during the ’80-‘90, have been interpreted aiming at filling-out the gap of information between surface data and seismological records (Porreca et al. , 2018). In the last decades, seismic reflection profiles have been extensively used in the Umbria-Marche region to constrain the geometry of seismogenic faults at depth, as well as the deep geological setting (Barchi and Mirabella, 2009). Seismic reflection data may represent a unique and unrepeatable source of information for the reconstruction of the regional geological model. However, their quality is extremely variable and, in some cases, poor, due to several factors (Mazzotti et al. , 2000). Therefore, we have recently focused our efforts onto twomain strategies to improve the data visualization and interpretability. The first is a dedicated data reprocessing, starting from the original shot gather dataset (Ercoli et al. , 2018) in particular aimed at optimizing static corrections and velocity models with modern algorithms. Here we present some preliminary results of the second strategy, namely the Seismic Attribute Analysis. It is a powerful tool frequently used in the Oil and Gas exploration (Chopra and Marfurt, 2018), but not often adopted for seismic data in seismotectonic research, apart in few GPR applications (Ercoli et al. , 2012, Ercoli et al. , 2015). In this work, we focused on two seismic profiles intercepting the two Quaternary basins of Norcia and Castelluccio di Norcia. After testing several attributes, we provide the best images obtained after the application of amplitude and phase-based attributes, that considerably enhanced the overall interpretability of seismic lines. Data and Method. The original dataset includes 97 2D seismic reflection profiles across the epicentral area. Within this dataset, we extracted two W-E lines, crossing the hypocentral area about four kilometers to the South of the Mw 6.5 hypocenter (Fig. 1). Fig. 1 - Location map of the seismic lines across the Norcia and Castelluccio di Norcia basins (Central Italy).