Landslide characterisation in Canada using interferometric SAR and combined SAR and TM images

In Canada and the United States the direct and indirect cost of the damages caused by landslides is about US 2.2 billion dollars a year. These slides are mainly the result of excessive precipitation or ground shaking from earthquakes. Developing new remote sensing techniques to identify and characterise landslides will assist in the current national landslide inventory and hazard mapping programs. This paper reports on the use of interferometric SAR, RADARSAT, and airborne SAR combined with Landsat, TM images to identify diagnostic features of landslides and their slope characteristics. The landslide types in Canada are found in different physiographic regions and are associated with certain kinds of soil and rock materials, geologic structures and topographic settings. Interferometric SAR images provided information on detail slope profiles of the large rock slides occurring on steep slopes and along faults in the Canadian Cordillera. From this image, faults, rock slumps, block slides, slide scars and debris slopes were identified. RADARSAT images with incidence angles varying from 40–59 degrees, particularly the fine mode images, are the most useful to identify landslide features, in mountainous areas. An interpretation of retrogressive slope failures on the shale banks of the Saskatchewan river was conducted using a combined Landsat TM and SAR images. Flow slides on sensitive marine clays were identified on airborne SAR images in the Ottawa valley. These examples show that several remote sensing techniques can assist in producing landslide inventory and risk assessment maps by providing the information on the morphological features of landslides.