The purpose of this study is to detect the locations of Slope failure caused by earthquakes and heavy rains in mountainous regions by using Satellite remote sensing technique.
Remote sensing is basically an effective method to capture the disaster situation due to a Large-scale disaster because it can safely observe wide damaged areas. We could not analyze small-scale slope failures by using conventional medium resolution satellite images in the past, however, we have now been able to analyze them by using recent high resolution satellite remote sensing technique. In the future, moreover, it is scheduled that new satellite with more high resolution will be launched and it is expect that we will be able to analyze damaged areas more in detail.
From this point of view, as a first step, we tried to detect the locations of slope failure by using images of AVNIR-2(Advanced Visible and Near Infrared Radiometer type 2)sensor loaded on ALOS (Advanced Land Observing Satellite)for four natural disasters i.e., the 2007 off Niigata-chuetsu earthquake, the 2008 Iwate-Miyagi inland earthquake, the 2009 Chugoku- Kyushu-hokubu heavy rain and the 2010 Shobara in Hiroshima prefecture heavy rain.
In detecting the locations, from the satellite images taken after the events, we first obtained two indices, i.e., INDVI(Inverse Normalized Difference Vegetation Index)which is newly proposed in this study and NDSI (Normalized Difference Soil Index). For each index, we determined three categories, i.e., soil, vegetation and water areas based on the range of pixel numbers which belong to these areas.
From the results, it was found that the proposed INDVI is the most suitable parameter to detect the locations of slope failure.
