Extraction of Bridge Damage in the 2016 Kumamoto Earthquake Using Airborne SAR Data

Airborne Synthetic Aperture Radar (SAR) sensors are suitable for collecting information in an emergency response phase since they can acquire high-resolution images regardless of weather and sunlight conditions. Due to the Kumamoto earthquakes on April 14 and 16, 2016, scores of bridges were damaged and around 200 landslides occurred. In this study, we set the target area in Minami-Aso Village, Kumamoto Prefecture, Japan, which was suffered from numerous landslides. The landslide areas including several affected bridges were investigated using the pre- and post-event Pi-SAR2 airborne SAR images. As a result, the HH polarization and the surface scattering component were found to be most suitable to detect landslides by the pre- and post-event difference. The collapsed bridges were also extracted properly using the contribution ratio of each scattering component within bridge outlines.