GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 1.2 157 Palano M.; 2015: On the present-day crustal stress, strain-rate fields and mantle anisotropy pattern of Italy . Geophys. J. Int., 200 (2), 969-985, DOI 10.1093/gji/ggu451. Savage J. C. and Simpson R. W.; 1997: Surface strain accumulation and the seismic moment tensor . Bull. Seismol. Soc. Am., 87, 1345-1353. Spampinato S., Ursino A., Barbano M. F., Pirrotta C., Rapisarda S., Larocca G. and Platania P.R.; 2017: A Reappraisal of Seismicity and Eruptions of Pantelleria Island and the Sicily Channel (Italy). Pure Appl. Geophys. 174, 2475– 2493, DOI 10.1007/s00024-017-1550-x Wiemer S.; 2001: A software package to analyze seismicity: ZMAP . Seismological Research Letters, 72(3), 373-382, DOI 10.1785/gssrl.72.3.373. SEISMOTECTONICS AND SEISMIC RISK IN SOUTHERN CALABRIA V. Tripodi 1 , A. Gervasi 2 , M. La Rocca 1 , F. Muto 1 1 DiBEST, Università della Calabria, Arcavacata (CS), Italy 2 Istituto Nazionale di Geofisica e Vulcanologia, INGV-CNT, Roma. DiBEST, Italy Introduction. Southern Calabria is one of the areas of the Mediterranean basin with the highest seismic risk. The Strait of Messina earthquake that occurred on the morning of December 28, 1908 is only the last catastrophic event. In fact this region suffered many destructions during the past centuries, caused by earthquakes of Imax XI. For example the seismic sequence that affected central-southern Calabria starting on February 5 1783 was one of the most desctructive occurred in Italy in historical time. The first historical information on the seismicity of Calabria, albeit with the uncertainties of the case, date back to the first century BC. The Greek geographer Strabone reported an earthquake that in 91 BC caused great damage at Reggio Calabria settlement (Boschi et al. , 1995). However, it is only since the late Middle Ages that more reliable information are available, while we must wait until the 17th century to have descriptions of the effects of earthquakes that are reliable and detailed enough to be used for studies on seismotectonic and seismic risk. The overall picture is a territory affected by a inhomogeneous seismic activity as regards both its spatial-temporal distribution and the maximum intensities manifested, giving rise to some of the most violent effects ever recorded in Europe. However, the current knowledge of the geodynamic and seismotectonic context of the area, which represent the cultural basis of the actions suitable for assessing and reducing the seismic risk, is still far from a completely satisfactory level. Many efforts are necessary with the aim to make possible, in a remote future, a deterministic prediction of the characteristics and evolution of seismic activity, the ultimate goal of all applied earthquake research. Geological structure of South Calabria. The southern sector of the Calabrian Block extends from the Straits of Catanzaro in the north to the southern extremity of Calabria (Fig. 1). It presents a highly articulated geological structure, characterized by the presence of a back-arc basin in its western portion, by a forearc basin in the east side and by a mountain range consisting of two crystalline massifs in contact, the Serre massif to the north and the Aspromonte massif to the south. From the geodynamic point of view the southern Calabria block is characterized by the subduction from ESE towards NNO and from the rollback of the ionic slab correlated to the collision between the African and European plates (Critelli, 1999; Bonardi et al. , 2001; Faccenna et al. , 2001a; Minelli and Faccenna, 2010; Critelli et al. , 2017). The migration of the Calabrian Block was driven by strike and oblique slip fault systems which produced the segmentation of the orogen over time and led to the current structural configuration with the formation of Plio-Pleistocene sedimentary basins placed longitudinally and transversely to the chain (Ghisetti, 1979, Ghisetti and Vezzani, 1981; Van Dijk et al. , 2000; Tansi et al. , 2007,