11:15 〜 11:30
[HGM04-08] Estimating three-dimensional motion of a creeping landslide from topographic data and associated land surface parameters
キーワード：creeping landslide, geomorphic change detection, optical flow, land-surface parameters
Recent advances in surveying technologies have allowed high precision measurement and monitoring of changes in the Earth's surface position over time. Lateral mass movements remain an under-explored aspect of topographic analyses despite the plethora of dynamic processes affecting surface position. This research introduces the use of a two-dimensional optical flow algorithm to estimate the three-dimensional relationships between a topographic surface and itself after displacement using a time series of bare-earth digital elevation models (DEMs). Several indices are derived from the motion fields estimated by the optical flow algorithm to define a set of properties that are used to quantitatively characterize surface motion. A preliminary investigation into the efficacy of these surface properties for analyzing dynamic topography was conducted on a creeping landslide in Biratori, Hokkaido, Japan. An accuracy assessment demonstrated strong agreement between observed and estimated displacements, with concordance correlation coefficients of 0.87 for both x- and y-axis displacement, and sub-metre root mean squared error of 0.47 m and 0.72 m for the x- and y-axis respectively. A segmentation algorithm was applied to the translation distance and azimuth angle properties to assess the accuracy with which these variables delineate the landslide. Segments overlapped with the landslide boundary area by up to 70%, and segments within the landslide boundary were consistently among the largest in the segment-area distribution. The results demonstrated how these surface properties can form simple and effective heuristics for analyzing creeping landslides with strong potential for other dynamic surface phenomena.