Engineering Geology Landslide Investigations and SAR Interferometry

We can distinguish three phases of using the SAR and other EO satellite data in landslide studies: 1. Surface characterisation, ie initial topographic and geomorphological classification, DEMs, photogrammetry (using Spot and Landsat); 2. Measurement of slow to extremely slow slope movements by means of SAR interferometry; 3. Systematic monitoring of temporal-spatial variations in some slide producing agents (eg, relative change detection in soil moisture, surface drainage, vegetation, and land-use). The most serious limitation for the practical or operational applications of current space technologies in landslide investigations appears to be the coarse resolution of satellite images. Thus the available EO satellite data could be best exploited for small scale landslide investigations. Thanks to a regular schedule and frequent coverage of large areas by EO systems, satellite images will be particulary attractive for regional landslide hazard zonation and possibly for preliminary warning. A reliable and timely warning requires the use of a continuous site-specific monitoring system. This is usually impractical in most situations due to high costs of in-situ operations. The development and routine introduction of EO methods which employ periodic change detection of slide producing agents thus seem to offer a cost effective alternative for providing initial wide area assessments of ground deformation susceptibility. This approach thus simply targets those areas where there is a potential hazard and where more detailed geotechnical investigations may ultimately be required.