PSI technique for analysing slow landslides: a useful tool to handle with care

Abstract

Persistent scatterers interferometry (PSI) based on the analysis of satellite synthetic aperture radar (SAR) data in the field of landslide mapping is becoming a widespread tool, commonly used together with traditional geomorphological survey techniques and other monitoring instruments. Having acquired permanent scatterers interferometry SAR (PSInSAR™) data since 2005, the Region of Liguria has in recent years carried out several operational tests to define the correct procedures to provide appropriate interpretations of PSI data sets with respect to landslide mapping and state of activity definition. These experiences have resulted in the elaboration of a semi-automatic procedure using spatial analysis tools provided by any commercial geographic information system (GIS) software to allow a quick overview of huge data and obtain indications of potentially unstable areas. An analysis of the results shows a good general congruity between the potentially unstable areas detected and landslide inventory maps, but also some anomalies.