Abstract
Airborne Synthetic Aperture Radar (SAR) imagery has widely been used for photogeologic interpretation because of its advantages such as all-weather imaging capability through clouds, high spatial resolution, and exaggeration effect of surface topography. Many previous papers reported that airborne SAR imagery is .especially useful to interpret lineaments, which is defined as linear surface topographic features that presumably reflect subsurface fractures including active faults. This paper investigates usefulness of the airborne SAR images to detect predefined and undefined active faults in Chubu district, Japan, and compares airborne and spaceborne SAR images for lineament interpretation.
The airborne SAR images used in this study was obtained in 1981 as a part of a nationwide geothermal assessment project conducted by NEDO (New Energy Development Organization). We extracted many lineaments by visual photogeologic interpretation on the SAR images of Chubu district, where many active faults have already been recognized. The extracted lineaments were compared with the active faults described in "Maps of Active Faults in Japan". In this comparison, we found that most of predefined active faults were clearly indicated as lineaments in the SAR images. On the other hand, there are many lineaments that have not been defined as active faults and many lineaments which may make a line with defined active faults. We also made a comparison between the airborne SAR images and the JERS-1 (Japanese Earth Resources Satellite-1) SAR images. Geometric distortion due to a smaller off-nadir angle of the JERS-1 SAR is a major problem in lineament interpretation.
