GNGTS 2011 SESSIONE 2.1 decrease of slip rates from the south towards the north. The maximum magnitude higher than 6.5 was assigned to 43 sources between both the fast and slow slipping faults. References Basili, R., Valensise G., Vannoli P., Burrato P., Fracassi U., Mariano S.,. Tiberti M.M., Boschi E.; 2008: The Database of Individual Seismogenic Sources (DISS), version 3: summarizing 20 years of research on ’s earthquake geology. Tectonophysics, doi: 10.1016/j.tecto.2007.04.014. DISS Working Group; 2010: Database of Individual Seismogenic Sources (DISS), Version 3.1.1: A compilation of potential sources for earthquakes larger than M 5.5 in Italy and surrounding areas. http://diss.rm.ingv.it/diss/, © INGV 2010 - Istituto Nazionale di Geofisica e Vulcanologia - All rights reserved. Leonard M.; 2010: Earthquake fault scaling; self-consistent relating of rupture length, width, average displacement, and moment release. Bull. Seism. Soc. Am., 100(5A):1971-1988 DOI: 10.1785/0120090189. Mai P. M., and Beroza G. C.; 2000: Source scaling properties from finite-fault rupture models. Bull. Seism. Soc. Am. 90,604 -615 DOI: 10.1785/0119990126. Wells D. L. and Coppersmith K. J.; 1994: New empirical relationships among magnitude, rupture length, rupture width, rupture area, and surface displacement. Bull. Seism. Soc. Am., 84, 974 - 1002.

ANALYSIS OF THE LOCAL SEISMIC HAZARD FOR THE STABILITY TESTS OF THE MAIN BANK OF THE PO RIVER L. Martelli 1, P. Severi 1, G. Biavati 1, S. Rosselli 1, R. Camassi 2, E. Ercolani 2, A. Marcellini 3, A. Tento 3, D. Gerosa 3, D. Albarello 4, F. Guerrini 4, E. Lunedei 4, D. Pileggi 4, F. Pergalani 5, M. Compagnoni 5, V. Fioravante 6, D. Giretti 6 1 Regione Emilia-Romagna, Servizio geologico, sismico e dei suoli, Italy 2 INGV, , Italy 3 CNR - IDPA, Italy 4 Dipartimento di Scienze della Terra, Università degli Studi di Siena, Italy 5 Dipartimento di Ingegneria Strutturale, Politecnico di Milano, Italy 6 Dipartimento di Ingegneria, Università degli Studi di Ferrara, Italy The embankment of the Po is structure considered of strategic importance for the purpose of civ- il protection. For this reason, the Po River Basin Authority (AdB Po) has received funding to carry out the stability of the embankment under seismic conditions in the municipalities characterized by the highest seismic hazard between Boretto (RE) and the mouth. According to the seismic classifi- cation then in force (OPCM 3274/2003), the municipalities with the highest seismic hazard, in the interest tract, are those classified in zone 3: Boretto, and in the Province, Carbonara Po, Sermide and Felonica in Mantua Province, Bondeno, Ferrara and Ro in Ferrara Province. The linear development of the embankment subject to seismic verification is about 90 km. To carry out that study the AdB Po has formalized an agreement with the Interregion- al Authority for the Po River (AIPO) and the Regional Governments, namely the Emilia-Romagna and Lombardia. The feasible project entrusts the coordination of activities to assess seismic hazard at the sites to the Geological, Seismic and Soil Survey of Emilia-Romagna Region (SGSS). The adopted procedure is derived from a previous study for the verification of stability under seismic conditions of the expansion areas of some tributaries of the Po in Lombardia and Emilia-Romagna. This study was carried out by a working group of geologists and engineers of Politecnico di Milano – DIS (PoliMI), DICeA- Florence University and SGSS, under the coordination of the ADB Po (Compagnoni et al., 2010; Pergalani et al., 2010, 2011). In particular, to define the site seismic hazard, geological. geophysical and seismotectonic inves- tigations were carried out in the following phases and activities. Definition of the geological and geophysical models (by the SGSS): - collection and analysis of previous data available, from public authorities (Provinces, Municipal- ities, AIPO, ...) or from professionals (geologists, engineers, ...); - review of deep seismic lines (ENI courtesy) for the identification of the main tectonic structures and the main seismic-stratigraphic horizons; - new in situ tests to define the internal characteristics of the bank and the stratigraphy of the

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ground, through drillings of several dozen of bore-holes with collection of samples for laboratory analysis and DH tests up to 30 m depth from the top of the bank and up to 50 m depth from the base of the bank, hundreds of CPTU and dozen of SCPT, seismic profiles with MASW and ReMi tests, electrical resistivity tests and 3 couples of bore-holes drillings up to depth of 150 m where CH were carried out; - monitoring of ambient vibrations to define the fundamental frequencies of the deposits (survey by DST-UniSI and CNR-IDPA): this kind of survey aims at the extensive preliminary mapping of main seismic impedance contrasts in the subsoil responsible for possible resonance phenomena and local seismic hazard increase; - description of the lithostratigraphic features through the reconstruction of more than 100 geolog- ic cross-sections, carried out along significant transects based on geological characteristics, vul- nerability conditions and urban exposure; - summary of the results of geological and geophysical surveys and ambient vibrations measures to define the seismic bedrock (activities carried out in collaboration with DST-UniSI and CNR- IDPA). Definition of the input motion: - review of the earthquakes catalogs (CPTI04, CPTI08), by INGV-BO, considering all the earth- quakes that have produced damage in Emilia-Romagna, to create site seismic histories and deter- mine updated parameters on localization and energy of earthquakes of interest; 7 minor historical earthquakes, not previously included in the available catalogs, have been recognized; - identification of two scenario earthquakes, one high magnitudeor generated by the front of the Apennine thrust or subalpine, a smaller representative of the seismicity next to the Po river; - analysis of the seismic hazard (by CNR-IDPA and DST-UniSI): this study aims at defining earth- quakes representative of local hazard by statistical disaggregation analysis carried by considering standard and macroseismic approaches; - definition of response spectra from analysis of seismic hazard and identification of the compatible recorded accelerograms deriving from Italian and European data-bases (by PoliMI, CNR-IDPA, UniFE, SGSS-RER). Definition of geotechnical parameters through laboratory analysis (activities coordinated by AIPO, performed at the geotechnical laboratories of AIPO, Parma University and Turin Polytech- nic Institute). Site seismic response tests through mono-dimensional numerical analyses able to have information about the expected amplifications in term of amplified accelerograms, amplifica- tion factors and amplified response spectra, for each geologic cross-sections (by PoliMI and UniFE). Key element for the geological structure is the buried high of the Ferrara Folds, with cul- mination just under the Po River, NW of the Ferrara city. The results of geological and geophysical surveys allowed to divide the 90 km of interest in 4 macro-areas, with homogeneous lithostratigraphic characteristics and increasing seismic hazard: - municipalities of Reggio Emilia Province (Boretto, Gualtieri and Guastalla); - municipalities of Mantua Province (Carbonara Po, Sermide and Felonica); - municipalities of Boretto and Ro (Ferrara Province); - municipality of Ferrara. The area 1 is characterized by a thick alluvial deposits, more than 500 m, result of different depositional cycles, consisting of alternating silty-clayey deposits of alluvial plain and sandy hori- zons, sometimes with fine conglomerates, of channel and levee; the geological substratum consists of marine and transition deposits of middle Pleistocene age. Approaching the structural high we observe a reduction of the total thickness of the alluvial sequence and local amalgamations of the sandy horizons; in particular: in zone 2 the thickness of alluvial deposits reduces, from north to south, from 400 to 250 m, in zone 3 further decreases and in zone 4 the total thickness of alluvial deposits is just over 100 m and at the depth of 130 m marl of Miocene age have been found. In addi- tion, moving towards the mouth (eastward) the conglomeratic horizons disappear. The geophysical surveys and the values of fundamental frequencies of deposits (from ambient vibrations measure-

222 GNGTS 2011 SESSIONE 2.1 ments) indicate that the depth of the roof of the seismic bedrock varies from about 150-160 m where the alluvial thickness at about 110-120 m at the top of the Ferrara high; note that, in any case, the seismic bedrock is already detectable in the alluvial sequence, corresponding to unconformities of upper part of the middle Pleistocene. The seismic hazard analysis suggests relatively low levels of ground shaking and macroseismic effects are expected in the whole area (expected intensities gen- erally do not exceed VII MCS but in the case of the Ferrara area where VIII MCS is reached). Seis- mic hazard increases from west to east in the 4 macro-areas described above. Hazard disaggrega- tion shows the most important contributions to seismic hazard in the eastern sector is provided by relatively small local earthquakes (magnitude around 5 within few tens of km) while in the western sector strong distant earthquakes (magnitude above 6 and distances of the order hundred of km or more) prevail. The input motion for the seismic response analysis and the stability tests has been defined considering the expected couple magnitude-distance, the expected peak ground accelera- tions and the expected response spectraThen, for each macro-area, 6 compatible accelerograms have been selected from Italian and European data-bases. Site seismic response tests in the 4 macro- areas show an amount of amplifications varying from 1.2 to 1.7 in term of amplification factors and, consequently, the amplified accelerograms and response spectra have been obtained to perform the stability analyses. The results of this study, just concluded, and the results of laboratory tests, coor- dinated by AIPO and performed at the geotechnical laboratories of the Turin Polytechnic Institute and Parma University, are the basis for the definition of the geotechnical model and stability tests of the main bank of the Po, which will be performed by the DICAM-Bologna University and the DICeA-Florence University, and the seismic microzoning (level 3). References Compagnoni M., Pergalani F., Madiai C., Simoni G., Vannucchi G., Martelli L. (2010) Verifiche sismiche di stabilità degli argini di alcune casse di espansione del fiume Po, 29° Convegno Nazionale del Gruppo Nazionale di Geofisica della Terra Solida, Prato. Pergalani F. (2010) Vulnerabilità sismica degli argini delle vasche di laminazione degli affluenti del fiume Po in Lombardia ed Emilia-Romagna, Giornata di Studio: “Rischio Sismico nella Pianura Padana”, Centro di studio e ricerca di sismologia applicata e dinamica strutturale – Università di Brescia – Museo Civico di Scienze Naturali di Brescia, 24 novembre 2010, Brescia. Pergalani F., Compagnoni M., Madiai C., Simoni G., Vannucchi G., Martelli L. (2011) Vulnerabilità sismica degli argini delle casse di laminazione di alcuni affluenti del Fiume Po, Ingegneria Sismica, in stampa.

MULTI-DISCIPLINARY APPROACH FOR THE SEISMIC VULNERABILITY OF UNDERGROUND EQUIPMENT AND PIPELINES G. Lanzano 1, G. Di Nunzio 1, F. Santucci de Magistris 1, G. Fabbrocino 1, E. Salzano 2 1 SAVA Department, Structural and Geotechnical Dynamics Lab., StreGa, University of Molise, Italy 2 Istituto di Ricerche sulla Combustione, CNR, Italy Introduction. Stringent requirements for the safety of industrial equipment are necessary because, frequently, a large amount of toxic and flammable materials is handled. This circumstance leads to perform structural design of hazardous materials storage and transport infrastructures tak- ing into account consequences of failures and the associated risk of loss of containment. Therefore, effective tools for prevision and mitigation of effects related to breaks or leaks, especially if induced by natural hazard such as earthquakes, are needed. This is the background of a multi-disciplinary study on the seismic vulnerability of some industrial equipment, like the pipelines, underground tanks and buried basins, whose main aspects are herein summarized. carried out. Observation of the seismic damages occurred to the industrial plants. In the last decades, the damages caused by the earthquakes were collected and registered trough the direct observations and the analyses of the consequences of the event. Concerning the industrial plants, well-document- ed post-earthquake reports were written down after major seismic events, starting from San Fran- cisco (1908) till Maule (2010). Based on the analysis of available reconnaissance reports, a collec- tion of damage cases were carried out, focusing on a specific class of components of industrial

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