GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 - POSTER GNGTS 2023 Formation; Centamore et alii, 1986) outcrops in the Monte 5 Querce ridge and the M.Subasio respectively. Among the long sequence of earthquakes that struck the valley (CPTI15, Rovida et al., 2016), this area experienced in the 19th century two major earthquakes with the epicentres here localized: the 13 January 1832 ME=6.3; I0=X, and the 12 February 1854 ME=5.6; I0=VII (Fig. 2b). In recent times the seismic sequences have affected the Apennine sector east of the NUV and the western Martani ridge (south of Monte Cinque Querce Ridge, Fig 1), hit the valley and the urbanized areas, such as the 26 September 1997 (Mw 6.0), often causing considerable damage to civil and industrial structures as well as to technological networks mainly due to local amplification effects. Data and Methods The ground subsidence occurring in the Northern sector of the Umbria Valley (Guzzetti et al., 2009) is measured using PS data generated by exploiting MInSAR techniques. The available archive of Permanent Scatterers was used to evaluate the spatial and temporal distribution of the soil subsidence. Up to 24 years of images acquired by the ERS1/2, ENVISAT, Sentinel-1 ESA (i.e, European Space Agency) and the COSMO-SkyMed ASI missions were processed in the framework of the MATTM-PST-A and the ESA-MENPHYS projects respectively. Land subsidence was compared with the water level in the well field located in the area of greatest subsidence (ARPA Umbria, https://apps.arpa.umbria.it/acqua/ content/Ground-Levels; Fig 2) Discussion and Conclusions The availability of large datasets of SAR satellite acquisitions and new technologies, based on advanced cloud computing implementing the multi-temporal differential interferometry technique, allows the observation of the earth deformation phenomena during the last decades with unprecedentedly reached time and areal extensions. In the Valle Umbria case, the artificial decrease of the hydraulic pressure has induced ground subsidence due to the compaction of sediments and the irreversible collapse of the aquifer, with a consequent risk of loss in the amount of available drinking water and for agricultural purposes. The displacement is evaluated at more than 1 m with up to 55 mm/year of ground velocity (Fig. 2a). The continuous raising of the groundwater level in the well present in the area of greatest deformation (Fig. 2b), suggests the achievement of a new equilibrium between pumping and natural recharge of the deep aquifer also due to a decrease in water withdrawals.