2013 Volume 33 Issue 1 Pages 1-12
Due to the limited time between earthquake occurrence and a tsunami reaching land, it is important for us to flee temporarily to buildings designated for tsunami escape such as mid-to-high-rise buildings. We attempted the use of aerial LiDAR data to assess the appropriateness of buildings to be used for tsunami escape in Asahi city, Chiba prefecture, which was damaged by the tsunami triggered during the March 11 earthquake. Our calculations were based on the dimensions of buildings designated as possible candidates for tsunami escape using aerial LiDAR data in predicted inundation areas. We then did an investigation to confirm the suitability of candidates. Firstly, the inundation height was estimated using VRS RTK-GNSS survey equipment in filed survey on August 26, 2012. Secondly, to correct aerial LiDAR data observed pre-earthquake, the surface deformation patterns were evaluated with InSAR technique using ALOS/PALSAR data. Thirdly, the spatial information of the predicted inundation area was simulated using a digital elevation model derived from aerial LiDAR data. Fourthly, the safety of the candidates for tsunami escape was calculated from the dimensions of the buildings measured using a digital feature model derived from aerial LiDAR data. Finally, the specific condition of the candidates for tsunami escape was confirmed by field survey on January 6, 2012. In conclusion, we found that candidate buildings for tsunami escape can effectively be determined using aerial LiDAR analysis. Moreover, the influence of ground height to affect the safety of the candidates was found to be a major factor.
