To extract the topographical characteristics of newly occurring slope collapses and landslides, it is necessary to perform geographic analysis based on topographical data before such calamities occur. However, topographical data are often not collected in such situations. In contrast, satellite images are regularly captured and can be used to obtain topographical data before such calamities occur. In this study, we compared the topographical data and orthophoto obtained from satellite images and aerial laser measurements of the plains and mountains in Hiroshima and Hyogo prefectures. From the analysis, it was observed from both the topographical data and orthophoto that the plain area had a residual of approximately 2 m. In contrast, some areas in the mountainous region had residuals of approximately 2 and 9 m.
In the volcanic region, the topography of fault displacement is unclear, so it is necessary to develop new methods in addition to conventional methods such as aerial photo interpretation and field surveys. In this study, we developed SPI distribution maps using slope and flow accumulation to investigate how active structures are represented around the 2008 Iwate-Miyagi Nairiku Earthquake (Mw 6.9) site. The Stream Power Indices (SPI) distribution is not as suitable for extracting edges as the slope and relative relief distributions, but it can clearly represent the knickpoints caused by active tectonics and differential erosion in a river system.