Abstract
Synthetic Aperture Radar Interferometry (InSAR) has now become a tried and tested method for detecting spatial distribution of surface displacement. The Advanced Land Observing Satellite (ALOS or "Daichi") was launched in January 2006, with three remote-sensing equipments including the Phased Array type L-band Synthetic Aperture Radar (PALSAR). Its high coherency enables us to detect high resolution surface displacement data. The Geographical Survey Institute analyzed the crustal movement of the Noto Hanto Earthquake in 2007 and estimated a detailed fault model using ALOS's PALSAR interferometric images. In addition to such wide-area elastic deformation caused by the faulting, we found a number of small patterns which seem to reflect local surface displacement. In combination with interpretation of landforms and field survey, we concluded that such patterns are indicating the existence of small scale - within few centimeters or few tens centimeters - movement of landslides triggered by the earthquake. We analyzed up-down and east-west components of displacement from two sets of SAR images and clarified the detailed features of surface movement that are consistent with the expected movement of landslides. We consider that the SAR interferometric images provide us exhaustive distribution of small scale surface displacement of landslides which is difficult to detect by the field reconnaissance or photo interpretation, and must be effective information for disaster prevention measures.
