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Landslide Detection Integrated System (LaDIS) based on in-situ and satellite SAR Interferometry measurements

Di Martire Diego1, Tessitore Serena1, Brancato Domenico2, Ciminelli Maria Grazia3, Costabile Salvatore4, Costantini Mario3, Graziano Gian Vito2, Minati Federico3, Ramondini Massimo5, Calcaterra Domenico1.
1 Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università degli Studi di Napoli Federico II, Largo San Marcellino 10, 80138 Napoli, Italy
2 Studio Associato Graziano & Masi, via Aquileia 34/a, 90144 Palermo, Italy
3 e-GEOS s.p.a., Via Cannizzaro 71, 00156 Roma, Italy.
4 Italian Ministry of Environment, Territory and Sea, Via Cristoforo Colombo 44, 00147 Roma, Italy.
5 Dipartimento di Ingegneria Civile, Edile e Ambientale, Università degli Studi di Napoli Federico II, via Claudio 21, 80125 Naples, Italy.
CATENA, Volume 137, Pages 406–421, February 2016
An integrated system to analyse slope instabilities over vast areas through the intercomparison of measurements obtained by in-situ and persistent scatterer (PS) interferometry processing of satellite synthetic aperture radar (SAR) data, is here introduced and tentatively named Landslide Detection Integrated System (LaDIS). The persistent scatterer pair (PSP) SAR interferometry technique was been used to process high-resolution SAR images acquired in the 2008-2011 time span by the COSMO-SkyMed satellite constellation, available in a 40 km × 40 km study area in the Palermo Province (Sicily region – Italy). Derived displacement rate estimates from COSMO-SkyMed PS measurements have been analysed in approximately 10% of the study area for landslide research. Within this area, according to the official landslide inventory map, extremely slow to very slow landslides are dominant, being favoured by the presence of heterogeneous clay formations characterized by poor mechanical properties. To prove COSMO-SkyMed PS displacement rates an engineering-geological approach was adopted, tailored to allow a continuous and rapid updating of landslide-inventory maps; to this aim a detailed geological field work has been performed. To guarantee an independent assessment, field surveys have been carried out without sharing information derived from PS data.
Almost half (49%) of the active unstable areas identified through COSMO-SkyMed PS measurements were confirmed by the field work. In an additional 26% of cases the greater sensitivity of the satellite has allowed to identify movements, even if very slow, that did not show superficial evidence.
A confirmation of the great potentialities of the latest generation of satellite systems also comes from the comparison with the current official landslide-inventory map, updated in 2006. Among the 58% of the total PS measurements that have been used to contour the landslides “in remote”, 84.3% falls outside the polygons of the failures detected in the existing maps, which implies a significant percentage of data to be associated to new landslides or extension of pre-existing landslides.
Advantages and drawbacks of exploiting COSMO-SkyMed X-band SAR data to study landslides over wide areas through the proposed approach are finally discussed.
Keywords:Landslide, Cosmo-SkyMed, interferometry SAR, geohazard mitigation
Figure 14. LaDIS results. 1) Landslide detected by satellite and confirmed by field survey;2) Landslide detected by satellite and partially confirmed by field survey;3) Landslide detected through PS measurements but not identified in the field survey;4) Landslide not detected through PS measurements but identified in the field survey. a) Giacalone; b) Bolognetta.