GNGTS 2013 - Atti del 32° Convegno Nazionale

The southeastern wall of the dismissed quarry was cleaned up and the outcropping fault was detected to display recent colluviums. The fault line appears capped by a shallow deposit. Dating of two samples from the faulted colluvium and from the post deformation deposit resulted in 2020-1993 B.C. and 607-680 A.D. respectively. A preliminary interpretation point to a reactivation of the fault right before the 607 A.D. Consistent evidence for a paleoevent around this age were previously assessed by Michetti et al. (1997) on the western section of the Pollino fault. Conclusions. In summary from above, we draw the following conclusions from this study: • trenching, performed on the Castrovillari and Pollino fault, shows evidence of historical paleoearthquakes on both the structures and confirms previous paleoseismological observations (Cinti et al. , 1997; Michetti et al. , 1997); • both the structures show evidence of paleoearthquakes, associated with surface faulting, whose time window is overlapping; • the observed fault displacement per event are consistent with paleoearthquakes equal or greater than M 6.5, as indicated also by the small displacement recorded during moderate earthquakes nearby (i.e. the M 5.6, 1998 Lauria earthquake; Michetti et al. , 2000b); • ERT survey is still a poorly exploited technique in paleoseismological studies, even if quick and cost effective: in this case electric tomography allowed to correctly locate trenching sites and imaged the deep geometry of the faults, suggesting the presence of tectonic offset also in areas where subtle geomorphologic evidence are present (i.e. Cozzo S. Elia site); • our observations confirm that the Pollino region has to be considered as active as other intramountain-basins in the Apennines, where Mw 6.5 to 7.0 earthquakes have been documented in the last 2000 years. The long-lasting historical seismic gap of the area, probably due to the incompleteness of the present-day catalogue, can be considerably filled took advantage by by the acquisition of punctual paleoseismological data. Acknowledgement. This study has benefited from funding provided by the Italian Presidenza del Consiglio dei Ministri - Dipartimento della Protezione Civile (DPC). This paper does not necessarily represent DPC official opinion and policies. References Caputo, R., Piscitelli S., Oliveto A., Rizzo E. and Lapenna V.; 2003: The use of electrical resistivity tomographies in active tectonics: examples from the Tyrnavos Basin, Greece. Journal of Geodynamics 36 (1), pp. 19-35. Cinti F.R., Cucci L., Pantosti D., D’Addezio G. and Meghraoui M.; 1997: A Major seismogenic fault in a ‘silent area’: the Castrovillari fault (southern Apennines, Italy). Geophys. J. Int. 130 , pp. 595–605. Cinti F.R., Moro M., Pantosti D., Cucci L. and D’Addezio G.; 2002: New constraints on the seismic history of the Castrovillari fault in the Pollino gap (Calabria, southern Italy). J. Seismology, 6, pp. 199-217. Ferreli L., Michetti A. M., Serva L. and Vittori E.; 1994: Terremoti olocenici lungo la Faglia del Pollino (Calabria Settentrionale): nota preliminare. In Paleosismologia e pericolosità sismica: stato delle conoscenze ed ipotesi di sviluppo. (ed. A. M. Michetti), CNR-GNDT (Gruppo Nazionale per la Difesa dai Terremoti) Rendiconti 2, pp. 65-88. ISIDe Working Group INGV; 2012: Italian Seismological Instrumental and parametric database Michetti A. M., Ferreli L., Serva L. and Vittori E.; 1997: Geological evidence for strong historical earthquakes in an “aseismic” region: the Pollino case (Southern Italy). J. Geodynamics, 24 (1-4), pp. 61-86. Michetti, A. M., L. Serva and E. Vittori.; 2000a: ITHACA Italy Hazard from Capable Faults: a database of active faults of the Italian onshore territory. CD-Rom and explicative notes, ANPA (copies available from E. Vittori: vittori@ anpa. it). Michetti A.M., Ferreli L., Esposito E., Porfido S., Blumetti A.M., Vittori E., Serva L. and Roberts G.P.; 2000b: Ground Effects during the 9 September 1998, Mw= 5.6 Lauria Earthquake and the Seismic Potential of the “Aseismic” Pollino Region in Southern Italy. Seismological Research Letters 71 (1), pp. 31-46. Rovida A., Camassi R., Gasperini P. and Stucchi M. (eds.); 2011: CPTI11, the 2011 version of the Parametric Catalogue of Italian Earthquakes. Milano, Bologna, http://emidius.mi.ingv.it/CPTI. DOI: 10.6092 /INGV.IT CPTI11. 114 GNGTS 2013 S essione 1.1