Subsidence activity maps derived from DInSAR data: Orihuela case study

Abstract

Abstract.A new methodology is proposed to produce subsidence activity maps based on the geostatistical analysis of persistent scatterer interferometry (PSI) data. PSI displacement measurements are interpolated based on conditional Sequential Gaussian Simulation (SGS) to calculate multiple equiprobable realizations of subsidence. The result from this process is a series of interpolated subsidence values, with an estimation of the spatial variability and a confidence level on the interpolation. These maps complement the PSI displacement map, improving the identification of wide subsiding areas at a regional scale. At a local scale, they can be used to identify buildings susceptible to suffer subsidence related damages. In order to do so, it is necessary to calculate the maximum differential settlement and the maximum angular distortion for each building of the study area. Based on PSIderived parameters those buildings in which the serviceability limit state has been exceeded, and where in situ forensic analysis should be made, can be automatically identified. This methodology has been tested in the city of Orihuela (SE Spain) for the study of historical buildings damaged during the last two decades by subsidence due to aquifer overexploitation. The qualitative evaluation of the results from the methodology carried out in buildings where damages have been reported shows a success rate of 100 %.

Building Deformation Assessment by Means of Persistent Scatterer Interferometry Analysis on a Landslide-Affected Area: The Volterra (Italy) Case Study

“…The maximum allowable settlement and angular distortion can be defined in relation to the type of structure (i.e., stiffness and use), foundation soil and foundation type (piles or direct foundations). For instance, a maximum angular distortion value of 3 × 10 −4 can be broadly defined for civil buildings on sandy and clayey terrain [24,29].…”

“…It is worth highlighting that the δLOS value is divided by the cosine of the satellite incidence angle in order to obtain the maximum vertical differential settlement (δv) of a given structure [24]. The angular distortion (β) we consider is related to the measured vertical settlement, and thus, it is computed as the ratio between δv and the distance (L) between the Dmin_LOS and Dmax_LOS measurement points:…”

“…The induced settlement and damage degree of buildings depend on their construction characteristics and on the geotechnical foundation ground properties. Therefore, some recent works combined InSAR tools with geotechnical features for identifying the potential occurrence of building damages [22][23][24].…”

“…In particular, Sanabria et al in [24] have proposed a method to develop a subsidence map by means of spatial interpolation of PSI displacement data acquired in the C-band, thus overcoming limitations related to the point-wise nature of PS information. This PSI-based methodology has been proven successful in identifying buildings susceptible to suffering subsidence-related damages in urban areas and estimating losses in terms of serviceability limit states.…”

“…Relying on the approach proposed by [24], we have applied a similar procedure on the southwestern sector of Volterra (Tuscany, Italy), a partially urbanized area where ground instability threatens the urban fabric and historical heritage, as presented in [25]. PSI data allowed us to locally detect the most unstable zones within the study area and consequently to identify the buildings subject to suffering terrain motions.…”