GNGTS 2018 - 37° Convegno Nazionale

394 GNGTS 2018 S essione 2.2 applying even Spectral Ratio method, showing a good correlation between the results, although the SR method is more influenced by problems related to waveform and frequency content of the seismic signal. References Gladwin, M. T. and Stacey, F. D.; 1974: Anelastic degradation of acoustic pulses in rock. Phys. Earth planet. Int., 8 , 332-336, doi.org/10.1016/0031-9201( 74)90041-7. Jongmans, D.; 1990: In-situ attenuation measurements in soils . Engineering Geology, Vol. 29 , Issue 2, pp. 99-118. Li, G. F., Zheng, H., Zhu, V. L., Wang, M. C. and Zhai, T. L.; 2016: Tomographic inversion of near-surface Q factor by combining surface and cross-hole seismic surveys. Applied Geophysics. Vol. 13 , Issue 1, pp. 93-102, doi. org/10.1007/s11770-016-0544-2. Morozov, I. and Ahmadi B.; 2015: Taxonomy of Q. Geophysics. Vol., 80 (1), pp. T41-T49, doi:10.1190/geo2013- 0446.1. Teng, T. L.; 1968: Attenuation of body waves and the Q-structure of the mantle : J. Geophys. Res., Vol. 73 , Issue 6, 2195-2208. doi.org/10.1029/JB073i006p02195. INSIGHTS ON THE DEEP STRUCTURE OF THE NORCIA BASIN (CENTRAL ITALY) BY COMBINATION OF GEOLOGICAL DATA AND SEISMIC NOISE MEASUREMENTS M. Ercoli 1 , J. Camilli 1 , G. Di Giulio 2 , M. Porreca 1 , M. Vassallo 2 , E. Ruggieri 1 1 Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Italy 2 Istituto Nazionale di Geofisica e Vulcanologia (INGV) - Sede di l’Aquila, Italy Introduction. The area located between Norcia and Castelluccio di Norcia has been affected by a strong shaking and damaging due to the complex seismic sequence occurred during the 2016-2017 (Chiaraluce et al. , 2017). Four regions (Umbria, Marche, Abruzzi and Lazio) have been interested by the events and were affected by important damaging. The city of Norcia has been historically stuck by several strong events, and the Mw 6.5 mainshock occurred the 30 th October 2016 has again produced strong damages of the city. It is evident how different areas of the basin have had different response to the shaking, so that parts of the city of Norcia and some little villages result severely damaged in comparison to others characterized by poor or absent damage (Galli et al. , 2017). The architecture of the basin surely has played an important role in regulating seismic response (Luzi et al. , 2018). Despite of numerous studies (e.g. microzonation 3th level) carried out during the last 40 years, the subsurface geology and structure of the region (Porreca et al. , 2018), as well as that of the Norcia basin is still debated. For this reason, we used an integrated approach combining geological and geophysical data, to investigate the deep structure of the Norcia basin aiming to better figure out possible relationships with its seismic response. Data and Method. In this work we applied an integrated approach including detailed geological mapping and geophysical surveys. The combination of new geological field data with stratigraphic data provided by wells and literature maps, provided indications on the main Quaternary lithostratigraphic units filling the basin; also, the location of the main faults has been drawn updating a geological map using this approach. In the same way, the geophysical data include information provided again by literature (e.g. Bindi et al. 2009; Bohm et al. , 2011; Luzi et al. , 2018), but the latter were also integrated by new data provided using passive noise measurements (Di Giulio et al. , 2003; Di Giulio et al. , 2016). An extensive campaign of the Norcia basin results in 54 new measurements of seismic noises, placed along two main transects in NW-SE and E-W directions (Fig.1). Four bidimensional arrays, made by eleven stations and located in the Northern sector of the basin, have been collected; two of them in the