GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione 1.1 177 Fig. 3 – Distribution of T- (redlines) and P-(blue lines) axes computed from focal mechanisms. Thin and thick lines lines are axes from earthquakes with depth < and >9 km, respectively. The length of each axis is proportional to the cosine of the plunge. As regards the second, more limited group of events distributed between 16-20 km depth, 9 of them (Ml<2.5), all with focal depth around 20 km, occurred in few hours onAugust 28, 2013. The fault plane solutions of two events from this swarm (located few km SW of Castelluccio inferiore, Fig. 3) are characterized by strike-slip kinematics with ~E-W and N-S nodal planes. Their T- and P-axes have NE-SW and NW-SE trends, respectively. Apart this swarm, all the remaining deep events with strike-slip to reverse-oblique kinematics are confined just to NE of the extensional fault belt (Fig. 3). These observations hinder the possibility that the deep strike-slip regime (Ferranti et al ., 2014), which characterize the eastern part of southern Italy (Fig. 1), is present also beneath its western part. References Boncio P., Mancini T., Lavecchia G., Selvaggi G; 2007: Seismotectonics of strike-slip earthquakes within the deep crust of southern Italy: Geometry, kinematics, stress field and crustal rheology of the Potenza 1990-1991 seismic sequences (Mmax 5.7). Tectonophysics, 445, 281-300. Brozzetti F., Lavecchia G., Mancini G., Milana G., Cardinali M.; 2009: Analysis of the 9 September 1998 Mw5.6 Mercure earthquake sequence (Southern Apennines, Italy): A multidisciplinary approach. Tectonophysics, 476, 210-225. Ferranti L., Palano M., Cannavò F., Mazzella M. E., Oldow J. S., Gueguen E., Mattia M., Monaco C.,; 2014: Rates of geodetic deformation across active faults in Southern Italy . Tectonophysics, 621, 101–122. Papanikolaou I. D., Roberts G. P.; 2007: Geometry, kinematics and deformation rates along the active normal fault system in the southern Apennines: Implications for fault growth . J. Struct. Geol., 29, 166-188. Rovida A., Locati M., Camassi R., Lolli B., Gasperini P. (eds), 2016. CPTI15, the 2015 version of the Parametric Catalogue of Italian Earthquakes. Istituto Nazionale di Geofisica e Vulcanologia. doi :http://doi.org/10.6092/INGV.IT-CPTI15 Totaro C., Seeber L., Waldhauser F., Steckeler M., Gervasi A., Guerra I., Orecchio B., &, Presti D., (2015). An Intense Earthquake Swarm in the Southernmost Apennines: Fault Architecture from High-Resolution Hypocenters and Focal Mechanisms. Bulletin of the Seismological Society of America, Vol.105, No.6. pp.