APPLICATION OF LIDAR, ALSM, AND AERIAL PHOTOGRAPHY TO RESOLVE BEDROCK STRUCTURE IN AREAS OF POOR EXPOSURE: EXAMPLES FROM THE KATALLA AREA, ALASKA

LiDAR and ALSM data along with various forms of aerial photography allow construction of improved regional maps of bedding, and fault traces in areas of poor outcrop. These regional maps can be used to develop 3D and 4D models either directly through 3D visualization or through reconstruction of cross-sections. With these remote sensing methods geological features such as fault scarps, bedding and fault traces can be identified and accurately traced in three dimensions. Once these geologic features are identified they can be studied through structural analysis. 3D and 4D models can be compared to current geologic data collected in the field, or current geologic data can be overlaid or plotted on these models to produce an accurate reconstruction of the structural history of an area. These kinds of data are being analyzed in the Katalla area in the St. Elias Mountains of southern Alaska. Here we emphasize results from draping of high resolution aerial photography onto a LiDAR DEM in the southern Alaskan data set acquired during the St. Elias Erosion and Tectonics Project (STEEP). The resultant 3D visualization, together with bare-ground LiDAR terrain models provide unprecedented abilities to visualize the geology in this complexly deformed terrain, as well as provide insights into the origins of large numbers of surface ruptures in the region.