GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione 1.1 129 are available for the study area due to the low magnitude of recorded events. Focal mechanisms provided for the Argentera-Mercantour Massif were computed starting from the accurate hypocentral parameters in output from HypoDD, on events for which at least 15 polarities were available. The final picture (Fig. 3) displays compressional focal solutions on the external and internal sectors of the Alps, extensional solutions in the central part, and strike-slip solutions towards the Ligurian-Provençal coast. The Argentera-Mercantour Massif shows extensional mechanisms with slight strike-slip component. In conclusion, the seismicity under the Argentera-Mercantour Massif apparently marks the geometry of the frontal thrusts controlling the Neogene exhumation of the massif. Based on our dataset of relocated earthquakes, the depth of these thrusts should range from 12 to 10 km. The extensional focal mechanisms observed under the massif suggest that these tectonic structures are now reactived under an extensional regime. On the northeastern side of the massif, the near- vertical Stura Fault is still active, and clearly identified down to 18 km depth. References Baroux E., Bethoux N., and Belier O., 2001. Analyses of the stress field in the southeastern France from earthquake focal mechanisms, Geophys. J. Int., 145, 336-348. Eva, E., Solarino, S., 1998. Variations of stress directions in the western Alpine arc. Geophys. J. Int. 135, 438–448. Larroque, C., Delouis, B., Godel, B., Nocquet, J.-M., 2009. ������ ����������� �� ��� ������������ ������������� Active deformation at the southwestern Alps–Ligurian basin junction (France–Italy boundary): evidence for recent change from compression to extension in the Argentera massif. Tectonophysics 467, 22–34 Malusà M.G., Polino R. and Zattin M., 2009. Strain portioning in the axial NWAlps since the Oligocene, Tectonics, 28, TC3005. Malusà M.G., Faccenna C., Baldwin S.L., Fitzgerald P.G., Rossetti F., Balestrieri M.L., Danišík M., Ellero A., Ottria G., Piromallo C., 2015. Contrasting styles of (U) HP rock exhumation along the Cenozoic Adria-Europe plate boundary (Western Alps, Calabria, Corsica). ������������� ����������� ����������� ��� �� ���������� Geochemistry, Geophysics, Geosystems, 16, 6, 1786-1824. Waldhauser F. and Ellsworth W. L., 2000. A double-difference earthquake location algorithm: method and application to the northern Hayward fault, California. Bull. Seismol. Soc. Am., 90, 1353-1368. 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