GNGTS 2018 - 37° Convegno Nazionale

170 GNGTS 2018 S essione 1.2 from the analysis of data from continuous and semi-continuous stations, using the GAMIT/ GLOBK software (Herring et al. , 2015) and following the three-step procedure described in Serpelloni et al. (2013). As shown in Fig. 1, across this sector of the ESA, GPS measurements show ~1 mm/yr of SE-NW shortening accommodated in ~40 km and a regional uplift of ~1 mm/yr in the Alps with maximum values close to 2 mm/yr in Valbelluna. We compare our results with the vertical rates from precise leveling measurements performed by the Istituto Geografico Militare (IGM; IGM- RG, 1978), over a distance of ~200 km, from the Venetian plain to the Southern Alps mountain belt, along the Fadalto Valley. The InSAR velocities have been tied to the GPS velocity field, rotated in a Adria-fixed reference frame (Serpelloni et al. , 2016), correcting for long-wavelength residual orbital errors (Zebker et al. ,1994), estimating a planar ramp and an offset between the two velocity datasets. This adjustment provides an improved agreement between InSAR and GPS velocities, projected along theLOS. The corrected ascending and descending LOS velocities have been combined in order to derive the vertical InSAR velocity component. This result has been compared with the vertical GPS and leveling rates, showing a notable agreement, as illustrated in Fig. 2. The integrated geodetic vertical velocity field allows to identify a velocity gradient of ~1.5 mm/yr occurring in less than 20 km of distance in correspondence of the Bassano-Valdobbiadene thrust (BT). In order to provide insights into the origin of the geodetic uplift, we developed a simple 2D dislocation model, jointly inverting GPS and InSAR velocities along a NNW-SSE oriented profile, crossing the Montello and Bassano-Valdobbiadene faults. Most of the fault geometry parameters are constrained by local instrumental seismicity, focal mechanisms (Danesi et al. , 2015) and the interpretation of the TRANSALP (Castellarin et al. , 2006) and geological profiles (Galadini et al. , 2005). We subsampled InSAR points in order to reduce the computational costs of the data inversion, and we apply a relative weight between GPS and InSAR datasets in order to calibrate the relative importance of the two different velocity fields. We jointly invert GPS and InSAR velocities along a SE-NW oriented profile from the venetian plain to the Dolomites in order Fig. 2 - Left: Vertical velocity field from InSAR data decomposition (dots), from GPS measurements (circles) and from the IGMI leveling data (diamonds). Right: cross section of vertical velocities along the A-B profile.