Detection and Monitoring of Slow Landslides Using Sentinel-1 Multi-temporal Interferometry Products

Landslide investigations can now benefit from high quality information obtainable using multi-temporal interferometry (MTI) techniques (e.g., PSInSAR, SBAS) and images acquired by satellite synthetic aperture radars (SAR). MTI is only little affected by bad weather and can provide long-term (years), regular (weekly-monthly), precise (mm) measurements of ground displacements over large areas (thousands of km2), with the possibility of exploiting the same series of radar images for regional to slope-scale investigations. Spatially dense measurements can be obtained (from hundreds to thousands data per km2). Furthermore, by offering regular global-scale coverage, improved temporal resolution (from 12 to 6 days) and free imagery, the new radar satellite mission Sentinel-1 of the European Space Agency (ESA) can now guarantee wider and more efficient application of MTI to landslide investigations. In this work we demonstrate for the first time the excellent potential of MTI based on Sentinel-1 for the detection and monitoring of slope instabilities affecting small hilltop towns in the Apennine Mountains of southern Italy. The is done by comparing the MTI results based on Sentinel-1 images with those based on ENVISAT data (ESA satellite retired few years ago). The comparison shows that by using Sentinel-1 imagery a few times higher density of radar targets (measurement points) can be obtained. Thanks to this and more frequent measurement capability of Sentinel-1, landslide detection and monitoring can be more effective.