GNGTS 2019 - Atti del 38° Convegno Nazionale

304 GNGTS 2019 S essione 2.1 Gomez Capera A.A., Santulin M., D’Amico M., D’Amico V., Locati M., Luzi L., Massa M., Puglia R., 2018. Macroseismic intensity to ground motion empirical relationships for Italy. In Proc. of XXXVII Gruppo Nazionale di Geofisica della Terra Solida (GNGTS), Trieste. Lanzano G, Puglia R, Russo E, Luzi L, Bindi D, Cotton F, D’Amico M, Felicetta C, Pacor F & ORFEUS WG5, 2018.  ESM strong-motion flat-file 2018 . Istituto Nazionale di Geofisica e Vulcanologia (INGV), Helmholtz- Zentrum Potsdam Deutsches GeoForschungsZentrum (GFZ), Observatories & Research Facilities for European Seismology (ORFEUS). Locati M., Camassi R., Rovida A., Ercolani E., Bernardini F., Castelli V., Caracciolo C.H., Tertulliani A., Rossi A., Azzaro R., D’Amico S., Conte S., Rocchetti E., 2016a. DBMI15, the 2015 version of the Italian Macroseismic Database. Istituto Nazionale di Geofisica e Vulcanologia. Luzi L., Pacor F., Puglia R., 2017. ItalianAccelerometricArchive v 2.3. Istituto Nazionale di Geofisica e Vulcanologia, Dipartimento della Protezione Civile Nazionale. doi: 10.13127/ITACA.2.3 Margottini C., Molin D. and Serva L., 1992. Intensity versus ground motion: A new approach using Italian data, Engineering Geology, 33:1:45-58. Rovida A., Locati M., Camassi R., Lolli B., Gasperini P. (eds), 2016. Catalogo Parametrico dei Terremoti Italiani (CPTI15). Istituto Nazionale di Geofisica e Vulcanologia (INGV). https://doi.org/10.6092/INGV.IT-CPTI15 Tertulliani A. ed Azzaro R. (a cura di), 2016. QUEST - Rilievo macrosismico per i terremoti nell’Italia centrale. Aggiornamento dopo le scosse del 26 e 30 ottobre 2016. Aggiornamento al 21 dicembre 2016, rapporto interno INGV Zanini M.A., Hofer L., Faleschini F., 2019. Reversible ground motion-to-intensity conversion equations based on the EMS98 scale, Engineering Structures, 180:310-320. LONG PERIOD SOIL AMPLIFICATION IN THE PO PLAIN (ITALY) TO ACCOUNT FOR SITE-EFFECTS IN REGIONAL PSHA C. Mascandola 1 , M. Massa 1 , S. Barani 2 , D. Albarello 3 1 INGV, Milano, Italy 2 DISTAV, Università degli Studi di Genova, Italy 3 DSFTA, Università degli Studi di Siena, Italy It is widely recognized that a significant proportion of the variability of earthquake ground motion is related to local geological conditions, which can modify the ground-motion amplitude, duration, and frequency. In particular, several investigations of deep sedimentary basins have highlighted that thick and soft sediments can strongly amplify long-period ground motion (> 1 s) (e.g., Anderson et al. , 1986; Joyner, 2000; Milana et al. , 2013; Massa and Augliera, 2013). The characteristics of long-period ground motion have gained growing interest in the civil engineering community because of the increase in the number of large-scale structures (i.e. tall buildings, long-span bridges etc.). In the framework of the site response estimation, both the S-wave velocity profile and the thickness of the soft sedimentary cover are considered fundamental parameters. At this regard, in a deep sedimentary basin at least three different kind of bedrock can be identified: geologic, engineering and seismic bedrock. The definition of bedrock is critical since it may provide very different reference conditions. The ‘geologic bedrock’ can be identified in correspondence with rock formations, whereas the ‘engineering bedrock’ can be identified based on the shear- wave velocity ( Vs ) value indicated in the current seismic code. Both the European and Italian seismic codes have defined the Vs transition from soft to stiff soil or rock ( i.e., soil category A) at 800 m/s (European Committee for Standardization, 2004; Ministero delle Infrastrutture e dei Trasporti, 2018). In this sense, the Vs threshold of 800 m/s marks the top of engineering bedrock. However, this is a conventional value and it might not correspond to significant variation in the mechanical properties of the subsoil materials. On the other hand, the seismic bedrock is defined by a marked seismic impedance contrast between soft and hard soils (or rock), which