GNGTS 2017 - 36° Convegno Nazionale

GNGTS 2017 S essione 1.1 29 a local reference frame (Palano et al. , 2017). In addition, by taking into account the observed horizontal velocity field and associated uncertainties, we computed the 2D strain-rate tensor over the investigated area. Because of the heterogeneous spatial distribution of our velocity field data, we adopted the method described in Shen et al. (2015) which, in interpolating the velocity field, introduces the spatial weighting function of data in various forms (e.g. uniform Gaussian or quadratic spatial weighting function), allowing to obtain finer resolution. Both velocity and strain-rate fields, while providing an update of the quantitative estimates of previously established first-order active kinematic features of the investigated area, highlight how information coming from episodic measurements are helpful to improve the network coverage and, consequently, to provide finer details on the current crustal deformation pattern. However, velocities estimated on a number of episodic benchmarks, although spanning a time interval generally longer than 10 years, are based on very few observations (only 3-4 measurements) and therefore are affected by larger uncertainties. To reduce these uncertainties as well as to improve the spatial resolution of the investigate area, additional measurements, carried out on all the benchmarks of the “IGM95 geodetic network”, are strictly required. Aknowledgments We thank the scientific and technical staff of INGV who continue to maintain the GPS network. We thank also Leica Geosystems S.P.A. (http://it.smartnet-eu.com ), NetGEO (www.netgeo.it ) Unavco facility (www. unavco.org) , Regione Calabria (http://gpscalabria.protezionecivilecalabria.it/) for providing free access to GPS data. References Billi A., Presti D., Faccenna C., Neri G. and Orecchio B.; 2007: Seismotectonics of the Nubia plate compressive margin in the south Tyrrhenian region, Italy: Clues for subduction inception . J. Geophys. Res., 112 , B08302, DOI:10.1029/2006JB004837. Billi A., Presti D., Orecchio B., Faccenna C. and Neri G.; 2010: Incipient extension along the active convergent margin of Nubia in Sicily, Italy: Cefalù-Etna seismic zone . Tectonics, 29 , TC4026, DOI:10.1029/2009TC002559. Dercourt J., Zonenshain L.P., Ricou L.-E., Kazmin V.G., Le Pichon X., Knipper A.L., Grandjacquet C., Sbortshikov I.M., Geyssant J., Lepvrier C., Pechersky D.H., Boulin J., Sibuet J.-C., Savostin L.A., Sorokthin O., Westphal M., Bazhenov M.L., Lauer J.P. and Biju-Duval B.; 1986: Geological evolution of the Tethys belt from the Atlantic to the Pamirs since the Lias . Tectonophysics, 123 , 241-315, DOI:10.1016/0040-1951(86)90199-X. Dewey J. F., Helman M. L., Knott S. D., Turco E. and Hutton D. H. W.; 1989: Kinematics of the western Mediterranean . Geol. Soc. London, Sp. Pub., 45 , 265-283, DOI:10.1144/GSL.SP.1989.045.01.15. Doglioni C.; 1991: A proposal for the kinematic modelling of west-dipping subductions - possible applications to the Tyrrhenian-Apennines system . Terra Nova, 3 , 423-434. Faccenna C., Becker T.W., Lucente F.P., Jolivet L. and Rossetti, F.; 2001: History of subduction and back-arc extension in the central Mediterranean . Geophys. J. Int., 145 , 809-820. DOI:10.1046/j.0956-540X.2001.01435.x. Farolfi G. and Del Ventisette C.; 2017: Strain rates in the Alpine Mediterranean region: insights from advanced techniques of data processing . GPS Solut., 21, 1027-1036, DOI: 10.1007/s10291-016-0588-z. Herring T. A., King R. W., Floyd M. A. and Mcclusky S. C.; 2015: Introduction to GAMIT/GLOBK, Release 10.6 . Massachusetts Institute of Technology, pp. 1-50. INGV RING Working Group, 2016: Rete integrata Nazionale GPS . INGV, DOI:10.13127/RING. Nocquet J.-M.; 2012: Present-day kinematics of the Mediterranean: A comprehensive overview of GPS results . Tectonophysics, 579 , 220-242, DOI:10.1016/j.tecto.2012.03.037. Palano M.; 2015: On the present-day crustal stress, strain-rate fields and mantle anisotropy pattern of Italy. Geophys. J. Int., 200 , 969-985, DOI:10.1093/gji/ggu451. Palano M., Ferranti L., Monaco C., Mattia M., Aloisi M., Bruno V., Cannavò F. and Siligato G.; 2012: GPS velocity and strain fields in Sicily and southern Calabria, Italy: Updated geodetic constraints on tectonic block interaction in the central Mediterranean . J. Geophys. Res., 117 , B07401, DOI:10.1029/2012JB009254. Palano M., Piromallo C., and Chiarabba C.; 2017: Surface imprint of toroidal flow at retreating slab edges: The first geodetic evidence in the Calabrian subduction system . Geophys. Res. Lett., 44 , doi:10.1002/2016GL071452. Rovida R., Camassi P., Gasperini P. and Stucchi M.; 2011: CPTI11, the 2011 version of the Parametric Catalogue of Italian Earthquakes . http://emidius.mi.ingv.it/CPTI , DOI:10.6092 /INGV.IT -CPTI11, Milano, Bologna. Shen Z.-K., Wang M., Zeng Y. and Wang F.; 2015: Optimal interpolation of spatially discretized geodetic data. Bull. Seismol. Soc. Am., 105 , 2117-2127, DOI:10.1785/0120140247. Spampinato L., Sciotto M., Cannata A., Cannavò F., La Spina A., Palano M., Salerno G.G., Privitera E. and Caltabiano T.; 2015: Multiparametric study of the February-April 2013 paroxysmal phase of Mt. Etna New South-East crater . Geochem. Geophys. Geosyst., 16 , DOI:10.1002/2015GC005795.