GNGTS 2016 - Atti del 35° Convegno Nazionale

44 GNGTS 2016 S essione A matrice and 106 other public buildings). About 50% of the inspected buildings resulted immediately usable, whereas 30% of them resulted unusable due to heavy damage. Finally, the coordination of the activities related to the damage and usability assessment, as well as to the immediate safety countermeasures of the mobile cultural heritage and the heritage buildings deserves to be mentioned for its complexity and peculiarity. This activity, especially addressed to the safeguard of churches, palaces and monumental buildings, such as municipality towers, is performed in strict collaboration with the Ministry of Cultural Heritage and the Firefighters Corps, and with the technical-scientific support of ReLUIS. Evaluation of the seismogenic potential in key areas of the central and southern Apennines through analysis of speleothem vulnerability L. Ferranti 1 , B. Pace 2 , M. Vasta 3 , A. Colella 1 , M. Ramondini 4 , D. Calcaterra 1 , S. Di Bianco 1 , A. Valentini 2 , J. De Massis 2 , P. Teodoro 2 , D. Berardi 5 , N. La Rocca 6 1 Dipartimento di Scienze della Terra, dell’Ambiente, e delle Risorse, Università degli Studi Federico II, Napoli, Italy 2 DiSPUTer, Università degli Studi G. d’Annunzio, Chieti, Italy 3 Dipartimento INGEO, Università degli Studi G. d’Annunzio, Chieti, Italy 4 Dipartimento di Ingegneria Civile, Edile ed Ambientale, Università degli Studi Federico II, Napoli, Italy 5 Associazione Geonaturalistica Gaia Montesilvano, Pescara, Italy 6 Gruppo Speleologico Sparviere, Alessandria del Carretto, Cosenza, Italy Introduction. Earthquake forecast and seismic hazard models are generally based on historical and instrumental seismicity. However, in regions characterized by moderate strain rates and by strong earthquakes with recurrence longer than the time span covered by historical catalogues, such as in many parts of theApennines, different approaches are desirable to provide an independent test of seismologically-based models. We used nonconventional methods, such as the so-called “Fragile Geological Features” (FGFs), and in particular cave speleothems, for assessing and improving existing paleoseismological databases and seismic hazard models for selected areas of the Apennines. The analysis of speleothem deformation (breakage or offset) is part of speleoseismological studies, which seek for evidence of past earthquake within the cave archive (Forti, 2001; Becker et al. , 2006). Radiometric dating of the deformation events can be performed with relative ease and thus “speleoseismic” events can be compared to historical seismicity catalogues (e. g. Forti and Postpischl, 1984), or be used to extend back in time the paleoseismological record (e.g. Delaby, 2001; Becker et al. , 2005; Kagan et al. , 2005). However, the difficulty in quantitative modelling of the observed deformation, and its direct attribution to a geometrically-constrained seismogenic source is a major issue (Lacave et al. , 2004; Becker et al. , 2006). Lacave et al. (2000) investigated the range of fundamental natural frequencies and the damping of speleothems, and established that most of the broken speleothems are a direct indicator of the peak ground acceleration (PGA) during past earthquakes. Based on the analysis of the mechanical behavior of speleothems through static tests, Lacave et al. (2004) stipulated the PDF (probability density functions) for the bending stress leading to rupture, and established different vulnerability curves (probability of breaking as a function of PGA) for speleothems according to their shapes. On the other hand, unbroken speleothems may be used to define an upper limit of the “strength” for earthquakes that could have ever occurred during the speleothems lifetime. Based on these results, we started developing speleothem-based vulnerability curves for selected areas within the axial seismogenic belt of the Apennines.