Interferometric Triherence for Ground Movements Monitoring

Minor movements - of the order of 10 cm - of earth surface often precede landslides. Interferometric techniques have a potential of detecting such movements before a landslide occurs. An interferometric quantity - called triherence - was adopted for mapping of points where the interferometric phase is stable over at least one triplet consisting of three consecutive SAR scenes in suitable interferometric conditions. The results from JERS and ASAR triplets of the two study sites suggest that the triherence measure enables to pick up some points in the landscape where the phase behaviour of SAR pixels is stable. Most of the stable points were identified in urban areas but many of them can also be found in natural areas. The initial hypothesis, that in case of sparse vegetation or sparse forest cover, some highly coherent scatterers might be found, seems to be pertinent even if it still needs to be thoroughly checked on the ground.