GNGTS 2015 - Atti del 34° Convegno Nazionale

GNGTS 2015 S essione 1.2 99 In particular, the velocities of the permanent stations situated on the Tyrrhenian margin indicate stability or uplift, while the sites on the Adriatic sector are characterized with a subsidence pattern. We have formulated different hypothesis in order to explain this particular pattern, the study in order to find the more plausible are still in progress; preliminary results are discussed during the meeting. Other interesting feature of the present vertical kinematic pattern showed in Fig. 2 it is be represented to the different movements of the sites located on the Tyrrhenian coast respect to the Adriatic sector. The permanent stations located on the first sector are characterized by negative rates between 2-4 mm/yr and the rates of the sites located on Sicily and south Calabrian area seem essentially stable (Fig. 2). Conversely the permanent stations situated on the Adriatic coasts are characterized with negative velocities lower than the Tyrrhenian margin or uplift. The present vertical kinematic fields observed in the Sardinia and Sicily islands are characterized to relatively low uplift, with some isolated sites with negative rates. The Venetian and Po Valley are mostly characterized by subsidence as shown in Fig. 2. In the first zone, subsidence rates range between 2 and 4 mm/yr, while the highest rates are observed in the eastern sector of the Po Plain (Fig. 3) with rates roughly ranging from 3 to 8 mm/yr. In the western Po Valley vertical negative velocities are instead relatively lower (about 1–3 mm/yr). It can be noted that the transition from subsidence in the eastern zone to low subsidence (or stability) in the western sector fairly corresponds to the Giudicarie fault system and its southwestward prosecution. This relevant difference between vertical movements in the Fig. 2 – Vertical kinematic patternobtainedconsidering the stations with an observation time span longer than 2.5 years. The colours of circles indicate the velocity amplitudes, following the chromatic scale on the left.