Urban areas are frequently affected by ground instabilities of various origins. The location of urban zonesaffected by ground instability phenomena is crucially important for hazard mitigation policies. Satellite-basedInterferometric Synthetic Aperture Radar (InSAR) has demonstrated its remarkable capability to detect andquantify ground and building motion in urban areas, especially since the development of AdvancedDifferential Interferometric SAR techniques (A-DInSAR). In fact, the high density of re.ectors like buildingsand infrastructures in urban areas improves the quality of the InSAR signal, allowing sub-centimetricdisplacements to be reliably detected. The A-DInSAR techniques allow urban zones affected by grounddeformation to be located and mapped, but clearly they are not able to point out the causes of the instabilityphenomena. These can only be highlighted by an integrated analysis of multidisciplinary data, like geological,geotechnical, SAR interferometric and historical data. The overlay of these data, which is possible within aGeographic Information System (GIS), is a useful tool to identify ground motion phenomena affecting urbanzones. In this study we apply this kind of approach to Caltanissetta, a provincial capital in Sicily (Italy), wherelocal damage has been detected. The reconstruction of the local near-surface geology shows the presence ofzones affected by local natural hazard factors, essentially due to the local presence of soils with poormechanical properties or swelling soils, high topographic gradients and steep slopes on loose soils. Processing17 ASAR-ENVISAT SAR images covering the time interval October 2002.December 2005 by means of an ADInSARprocedure, the Caltanissetta deformation map has been realized. It shows that most of the city isstable, with the exception of three zones, situated in the northwestern, northeastern and southern parts of thecity, respectively. Two of them, characterized by high topographic gradients and steep slopes on sandy soils,are affected by subsidence ground motion. An uplift motion is recognized in the other zone, characterized bythe local presence of expansible clays. Geotechnical swelling tests carried out on them have shown a swellingbehavior. On site surveys have highlighted the presence of damage in the zones affected by ground motion.© 2008 Elsevier B.V. All rights reserved.
|Numero di pagine||11|
|Stato di pubblicazione||Published - 2008|
All Science Journal Classification (ASJC) codes
- Geotechnical Engineering and Engineering Geology