GNGTS 2015 - Atti del 34° Convegno Nazionale

10 GNGTS 2015 S essione 2.1 Some results. One of the targets of the INGV-DPC V3 Project is the probabilistic assessment of seismic hazard in the Etna region due to local volcano-tectonic earthquakes. This activity represents the extension of analyses undertaken in previous projects, based on the use of macroseismic intensity data. The approach we adopted in this work follows procedures used worldwide for traditional and innovative PSHA, and considers a large data set of input parameters (geological data, instrumental seismicity, GMPE, site response etc.). The hazard maps we computed are referred to an exceeding probability of 10% for short- mid exposure times - 5, 10 and 30 years - and do not take into account the contribution of regional seismicity, that is responsible for the maximum shaking expected in this area for an exposure period of 50 years (Stucchi et al. , 2011). Fig. 2 reports some outputs of Branch 3 for 10 and 30 years, referred to the BPT model and not including the aforementioned site effects. The comparison shows that PGA obtained by using only the geometric-kinematic characterization of the seismic sources, is twice with respect the one calculated by the historical-instrumental earthquake data. Examples of the contribution of the site amplification coefficients in a model of areal sources as depicted in Branch 1, is shown in Fig. 3. It clearly illustrates how amplification due to local site conditions can jeopardize the expected ground motion at rock reference sites, producing expected PGA values about twice with respect to the rock-reference site. Even if these results must be considered still preliminary, they represent a first example of new generation, site-specific seismic hazard maps suitable for civil protection purpose to define priorities of retrofitting at a local scale, complementary with those calculated for the national territory. References Alparone S., Maiolino V., Mostaccio A., Scaltrito A., Ursino A., Barberi G., D’Amico S., Di Grazia G., Giampiccolo E., Musumeci C., Scarfì L. and Zuccarello L.; 2015: Instrumental seismic catalogue of Mt Etna earthquakes (Sicily, Italy): ten years (2000-2010) of instrumental recordings. ���� ��������� Ann. Geophys., 58 (3), DOI 10.4401/ag-6591. Azzaro R., Barbano M. S., D’Amico S., Tuvè T., Albarello D. and D’Amico V.; 2008: First studies of probabilistic seismic hazard assessment in the volcanic region of Mt. Etna (Southern Italy) by means of macroseismic intensities . Boll. Geof. Teor. App., 49 (1), 77-91. Azzaro R., D’Amico S. and Tuvè T.; 2011: Estimating the magnitude of historical earthquakes from macroseismic intensity data: new relationships for the volcanic region of Mount Etna (Italy). Seism. Res. Lett., 82 (4), 533- 544. Azzaro R., Branca S., Gwinner K. and Coltelli M.; 2012a: The volcano-tectonic map of Etna volcano, 1:100.000 scale: an integrated approach based on a morphotectonic analysis from high-resolution DEM constrained by geologic, active faulting and seismotectonic data. Italian . J. Geosc., 131 (1), 153-170. Azzaro R., D’Amico S. and Tuvè T.; 2015: Seismic hazard assessment in the volcanic region of Mt. Etna (Italy): a probabilistic approach based on macroseismic data applied to volcano-tectonic seismicity. Bull. Earth. Eng., DOI 10.1007/s10518-015-9806-2. Azzaro R., D’Amico S., Peruzza L. and Tuvè T.; 2012b: Earthquakes and faults at Mt. Etna (Southern Italy): problems and perspectives for a time-dependent probabilistic seismic hazard assessment in a volcanic region. Boll. Geof. Teor. App., 53 (1), 75-88. Azzaro R., D’Amico S., Peruzza L. and Tuvè T.; 2013: Probabilistic seismic hazard at Mt. Etna (Italy): The contribution of local fault activity in mid-term assessment. J. Volcanol. Geoth. Res., 251 , 158-169. Azzaro R., D’Amico S., Pace B. and Peruzza L.; 2014: Estimating the expected seismicity rates of volcano-tectonic earthquakes at Mt. Etna (Italy) by a geometric-kinematic approach. ������ ��������� �� ��������� ����� ����� Gruppo Nazionale di Geofisica della Terra Solida, Atti del 33° Convegno Nazionale, Tema 1: Geodinamica, 20-25. Bindi D., Pacor F., Luzi L., Puglia R., Massa M., Ameri G. and Paolucci R.; 2011: Ground motion prediction equations derived from the Italian strong motion database. Bull. Earth. Eng., 9 , 1899-1920, DOI 10.1007/s10518-011-9313- z. Boore D.M. and Atkinson G.M.; 2008: Ground-motion prediction equations for the average horizontal component of PGA, PGV, and 5%-damped PSA at spectral periods between 0.01 s and 100 s. Earthq. �������� Spectra, 24 , 99-138. CMTE Working Group; 2014: Catalogo Macrosismico dei Terremoti Etnei dal 1832 al 2013. INGV, Catania, http:// www.ct.ingv.it/macro/http: / /www.ct.ingv.it/macro/ Grünthal G. (ed.); 1998: European Macroseismic Scale 1998 (EMS-98). �������� ������������� ����������� European Seismological Commission, subcommission on Engineering Seismology, working Group Macroseismic Scales. ������� �� ��������� ������� Conseil de l’Europe. Cahiers