DETECTION OF FAULT SCARPS IN LOUISIANA AND SOUTH TEXAS USING LIDAR DATA

Light detection and ranging (LIDAR) data is available for over 1,450 quarter quads covering most of south Louisiana as well as the Alexandria area. The statewide LIDAR project will image most of the state and cover an area of approximately 50,000 sq. mi. and about 3,500 quarter quadrangles. We have developed software to process this data using a suite of algorithms designed to bring out specific features, including scarp location and character. Scarp locations are compared to the location of known faults. Results show that some scarps are connecting faults or extensions to known faults. Other scarps are identified as likely faults based on signatures which match those of known faults.

The software has been used to identify scarp features less than one meter in height having the suspected fault signature. Inspection of one of these scarps south of De Quincy, Louisiana showed disruption in the highway surface in the character indicated by LIDAR imagery. An area of special interest is the Walker, Louisiana quadrangle. Complex faulting relationships of LIDAR data for this quadrangle include a relay ramp to the north and complex faulting and connection patterns throughout. In coastal Louisiana, low lying areas provide special challenges due to the effects of low relief. LIDAR data for Harris County, Texas has also been processed by the software. Known blind faults are visible in the resulting imagery.

LIDAR data is useful in the identification and mapping of likely fault scarps. However, confirmation that the scarps are fault related will require the use of subsurface data.