GNGTS 2016 - Atti del 35° Convegno Nazionale

46 GNGTS 2016 S essione A matrice modelling of the main collapsed speleothem. The horizontal ground acceleration resulting in failure and the natural frequency of the speleothem were assessed by the FEM modelling. The results suggest either the Liri or the Velino fault as the most probable causative fault of the cave speleothem collapses recorded ~4-5 ka ago. Noteworthy, the time range bracketed for the speleothem deformation is well consistent with a period of clustered slip recorded by cosmogenic dating of the Velino-Magnola fault scarp (Schlagenhauf et al. , 2011). In summary, our research contributes to assess the existence or lack of past earthquakes within the axial seismogenic belt of the Apennines. As a matter of fact, the Grotta Cola lies just west of the Fucino plain, where historical and modern seismic deformation of the central Apennines seismic belt has concentrated. Definition of the upper threshold for seismic shaking, as in the case for the recent behaviour of the Pollino region, can help reducing overestimated risks and calls for a fault-based revision of seismic hazard maps. References Becker, A., M. Ferry, Monecke K.; 2005: Multiarchive paleoseismic record of late Pleistocene and Holocene strong earthquakes in Switzerland. Tectonophysics, 400, 153-177. Becker, A., C. A. Davenport, U. Eichenberger, E. Gilli, P.-Y. Jeannin, Lacave C.; 2006: Speleoseismology: A critical perspective. J Seismol.,10 , 371-388. Delaby S.; 2001: Palaeoseismic investigations in Belgian caves . Netherlands J. Geosciences, 80(3-4), 323– 332. Ferranti L., S. Improta, L. Maschio, Vittori E.; 1997: Attività tettonica recente nel massiccio del Pollino suggerita dallo studio di speleotemi fratturati. Il Quaternario, 10 (2), 501-504. Ferranti L., Maschio L.; 2007: Ri cerche speleosismologiche nel massiccio del Pollino, Appennino Meridionale . Atti I Convegno Regionale di Speleologia “Campania Speleologica”, 1-3 Giugno, Oliveto Citra (SA), 201-215. Forti P.; 2001: Seismotectonic and paleoseismic studies from speleothems : The state of the art. Netherlands J Geosciences, 80(3-4), 175–185. Forti P., Postpischl D.; 1984: Seismotectonic and paleoseismic analyses using karst sediments . Mar. Geol., 55, 145- 161 . Kagan E. J., A. Agnon, M. Bar-Matthews, Ayalon A.; 2005: Dating large infrequent earthquakes by damaged cave deposits. Geology, 33(4), 261-264. Lacave, C., A. Levret, Koller M.; 2000: Measurements of natural frequencies and damping of speleothems . Proc. of the 12th World Conference on Earthquake Engineering, Auckland, New-Zealand, paper 2118. Lacave C., M.G. Koller, Egozcue J.J.; 2004: What can be concluded about seismic history from broken and unbroken speleothems? J. Earthquake Engineering, 8(3), 431-455. Lacave C., B. Sadier, J.J. Delannoy, C. Nehme, J.J. Egozcue; 2012: The use of speleothems to better constrain long return period seismic hazard in Lebanon . Proc. of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal. Roberts G.P., Michetti A.M.; 2004: Spatial and temporal variations in growth rates along active normal fault Systems: an example from Lazio-Abruzzo, central Italy . J. Struct. Geol., 26 , 339–376. MPS Working Group; 2004: Redazione della mappa di pericolosità sismica prevista dall’Ordinanza PCM 3274 del 20 marzo 2003 . Rapporto Conclusivo per il Dipartimento della Protezione Civile, INGV, Milano- Roma, 2004 april. 65 p. Schlagenhauf, A., I. Manighetti, L. Benedetti, Y. Gaudemer, R. Finkel, J. Malavieille, Pou K.; 2011: Earthquake supercycles in Central Italy, inferred from 36Cl exposure dating. Earth Plan. Scie. Letters 307 , 487–500.