Application of PSI technique to landslide monitoring in the Daunia mountains, Italy

F. BOVENGA, L. GUERRIERO, R. NUTRICATO, A. REFICE, J. WASOWSKI, 2006, Application of PSI technique to landslide monitoring in the Daunia mountains, Italy, FRINGE 2005, Frascati (Roma), Italy, 28 November - 2 December 2005,

Persistent Scatterers Interferometry (PSI) techniques allow to detect and monitor millimetric displacements occurring on selected point targets exhibiting coherent radar backscattering properties (mainly buildings and other man-made structures). The technique is sensitive to the number and spatial distribution of point targets and, therefore, particular care must be used when dealing with scarcely-urbanized areas. In the present work we apply the SPINUA (Stable Point INterferometry over Un-urbanised Areas) PSI processing technique [1] to the Daunia region located in Southern Apennines, Italy. This region includes several isolated small hill-top towns affected by slope instability problems. We selected for the analysis an area of 25×25 km2, enclosing 10 urban centres. A dataset of both descending (84) and ascending (51) ERS-1/2 acquisitions has been processed to allow investigation of slopes with a wide distribution of facing directions. In order to ensure an adequate distribution of coherent points for a reliable estimation of the atmospheric signal, the analysis has been limited to small image windows which enclose urban areas. This strategy, which has been also applied to other similar test sites [2], is justified by the fact that landslides with the highest socio-economic impact are those involving the urban centres. The density of the detected stable targets resulted suitable for 8 of the 10 investigated town areas, with a very good coverage of urban structures in 5 cases. The remaining 2 towns show a low number of PS, making difficult the detection of displacements. These outcomes could depend on the geometrical distribution of the coherent structures potentially corresponding to the PS. Although in several cases the displacement fields show clear evidence of moving objects located on urban and peri-urban areas, local knowledge of the investigated area and in situ inspections are required in order to interpret correctly the significance of PS motion data and to identify the main mechanism of the detected deformations.

Data from