Inferring sedimentary basin structure from multitemporal InSAR mapping of urban land subsidence: the Vallès Basin (Barcelona, Spain)

Land subsidence in the Vallès Depression (north of Barcelona) was investigated using multi-temporal PS-InSAR analysis based on ENVISAT (2003–2010), TerraSAR-X (2007–2011), and Sentinel-1 (2015–2020) satellite data. The resulting displacement maps reveal subsidence processes related to the presence of highly compressible layers and high groundwater extraction rates, which varied throughout the study period. In the northeastern sector, between Sabadell and Palau Solità i Plegamans, SW–NE-oriented bands with opposite ground-movement trends were identified. This pattern is interpreted as having a tectonic origin, as its orientation coincides with the structural features that bound the Vallès Depression. Field surveys confirmed the presence of pre-existing fractures and structural damage in buildings along these lineaments. The observations are consistent with subsidence and earth-fissure mechanisms controlled by tectonic structures that compartmentalize sediments with different compressibility. This study demonstrates the capability of PS-InSAR to identify structural features covered by compressible sediments beneath urbanized areas when strong contrasts in ground deformation occur between adjacent zones.