GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.3 GNGTS 2023 Donato (1999) who only considered isostatic effects associated with the remote ice sheets, thus neglecting the possible role of the Würm Alpine glacier. In this work, we review previously published results on sea-level change and vertical land motion in the Northern Adriatic, and we present our estimates of vertical velocities based on publicly available geodetic time series, distributed from the Nevada Geodetic Laboratory (NGL) at the University of Nevada, Reno ( http://geodesy.unr.edu/index.php ) , through analysis of 45 GNSS sites, which cover a region ranging from the Po delta to Trieste (Fig.1). We rely upon the tide gauges data made publicly available by the Permanent Service for Mean Sea Level (PSMSL, http://www.pol.ac.uk/psmsl ) , to analyze the records of Trieste and Venice, that represent the longest spanning records in the northern Adriatic Sea (Fig. 2). Furthermore, taking advantage of the recent publication of updated deglaciation chronologies for the far field late-Pleistocene ice sheets, ICE-7G (VM7) developed by Roy and Peltier (2015) and Roy and Peltier (2017) and for the near-field alpine ice complex, developed by Seguinot at al. (2018), we produce up-to-date estimates of the present-day rates of GIA-induced relative sea-level variations and vertical displacements in the northern Adriatic Sea and in the Venetian Lagoon (Fig.3). These rates are then compared with observed geodetic rates and with the tide gauges data. From high-resolution numerical simulations (Spada and Melini, 2019a, b), we find that GIA is responsible for a complex pattern of geodetic signals across the northern Adriatic Sea and the Venetian Lagoon. The modeled GIA rates are of the order of fractions of mm yr -1 , generally small, but not negligible, compared to the signals observed at local tide gauges and at GNSS. Our results indicate that, while GIA represents a second-order mechanism among those responsible for present-day land movements and relative sea-level variations in the northern Adriatic Sea, its contribution needs to be taken into account for a correct interpretation of the observed geodetic variations. Acknowledgements All figures have been drawn using the Generic Mapping Tools (GMT) of Wessel and Smith (1998). We acknowledge PSMSL for making available the tide gauge data available from http://www.psmsl.org . The Nevada Geodetic Laboratory is acknowledged for making available the GPS data from the web page http://geodesy.unr.edu/index.php . We thank Open Physics Hub (OPH) of DIFA (Dipartimento di Fisica e Astronomia “Augusto Righi”) of the Alma Mater Studiorum Università di Bologna for providing support with the Data Analysis cluster “BladeRunner” hosted in the Tier-1 server room of the INFN-CNAF. REFERENCES Carminati E., Di Donato G.; 1999: Separating natural and anthropogenic vertical movements in fast subsiding areas: the Po plain (N. Italy) case . Geophysical Research Letters, 26(15), 2291-2294. Clark J. A., Farrell W. E., Peltier W. R.; 1978: Global changes in postglacial sea level: A numerical calculation1 . Quaternary Research, 9(3), 265-287.