MONITORING GROWTH OF THE DAISETTA, TEXAS SINKHOLE WITH TERRESTRIAL LASER SCANNING, CLOSE RANGE DIGITAL PHOTOGRAPHY, AND GPS

On 7 May, 2008 a major sinkhole developed in Daisetta, Texas located about 60 miles northeast of Houston. The sinkhole formed by collapse of a salt dome and grew from a minor hole to a diameter reported in the media of over 200 m and a depth of over 75 m during the course of a single day. The collapse consumed several vehicles, drilling equipment, several oil tanks, and resulted in the destruction of several buildings. In May, 2008, personnel from the Cybermapping Laboratory in the Geosciences Department at the University of Texas at Dallas mobilized and deployed a Riegl LPM 800 HA laser profiler, a TOPCON Hyperlite RTK-GPS system, several camera systems, and a TOPCON IS Imaging Total Station to image and quantitatively assess the size of the collapse. Several overlapping scans with several million points were carried out around the sinkhole with the LPM and numerous digital photographs taken from a variety of locations. The TOPCON IS provided control for integrating LiDAR scans and for registration of digital photographs to the LiDAR image. RTK GPS was used to define global control points because the base stations were tied globally with the NOAA NGS OPUS processing of the reference stations. The integrated survey was accomplished in one day. The point cloud laser data were merged with Polyworks and a triangulated mesh (TIN) created. The control on the photos was positioned to the TIN using UTD software at an accuracy of one pixel. The result is an accurate 3D photorealistic (virtual) model of the entire sinkhole. The sinkhole had been flooded by water mainly due to Hurricane Ike and was reoccupied in November and a new 3D model developed to allow comparison with the physiographic feature measured in May. The changes between the two observations were assessed to develop a quantitative assessment of growth of the hole over the intervening months. Significant vertical and horizontal changes were observed and the sinkhole appears to have increased in size. Monitoring of the Daisetta sinkhole provides the opportunity to develop protocols and workflows for near real-time measurement and quantitative assessment of change associated with geologic hazards.