Recent Advances in Terrestrial Lidar Applications in Geotechnical Earthquake Engineering

During the past five years, geotechnical earthquake engineering and ground deformation research has benefited from the advent of terrestrial LIDAR technology, a revolutionary tool for characterizing fine-scale changes in topography. For ground deformation research, LIDAR is particularly useful for characterizing the dimensions of failures and for monitoring subtle deformations through time. Tripod mounted LIDAR systems have accuracies of approximately 0.4-2.0 cm, and can illuminate targets up to one kilometer away from the sensor. During several minutes of LIDAR scanning, millions of survey position points are collected and processed into an ultra-high resolution terrain model. During earthquake reconnaissance efforts, the detailed failure morphologies of landslides and liquefaction sites can be measured remotely and in a way that is either impractical or impossible by conventional survey means. The ultra-high resolution imagery of the complex surface morphology of ground failures allows the exploration and visualization of damage on a computer in orientations and scales not previously possible. Detailed understanding of the ground surface morphology allows for better numerical modeling of potential failure modes, deformation patterns, and morphologies. Finally, LIDAR allows for the permanent archiving of 3-D terrain models. In this paper, we present the evaluation of the accuracy, bias and dispersion of LIDAR data under controlled experimental conditions. Field applications of LIDAR-damage visualization and analysis are presented from data gathered during the 2004 Niigata Chuetsu (M6.6) earthquake and the 2007-2008 PARI-Ishikari, Hokkaido blast-liquefaction experiment