Search and Discovery Article #50034 (2006)
Posted July 15, 2006
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1University of Houston; currently Schlumberger, Houston ([email protected])
Over 300 active faults intersect the earth's surface in the Houston Metropolitan area. They cause damage to man-made structures such as roads, pipelines and buildings. We used LIDAR DEM images from the 2002 Tropical Storm Allison Recovery Project (TSARP) to examine known faults and to search for others that may have been overlooked in previous studies. We used hill-shading as the primary visualization method for locating the faults. Later we examined them in the field. At some locations fault deformation and associated damage were evident, while in other locations field expression of the fault was subtle and the presence of a fault was difficult to confirm. In some areas we used refined grids, using both raw data and supplied DEM, to better define known faults and to identify previously unknown faults.
Proper documentation of active surface faults is important so that developers can avoid building in the zone of disturbed ground along them. In some cases developers and builders have taken steps to avoid construction on fault traces, often by leaving the land as an open greenbelt or as a storm water detention pond. In other cases structures have been built unknowingly within fault hazard bands.
LIDAR DEM of Harris County, with LIDAR mapped faults and salt dome locations.
Proposed model for Houston area faults, showing relationship to salt in subsurface. The active surface faults are shown as continuing downward into growth faults. The growth faults sole out in structures resulting from the withdrawal of salt. Some of the salt rises in salt domes downdip of the faults.
Long Point Fault at Bunker Hill. (a) LIDAR; (b) LIDAR hillshade; (c) profile along Bunker Hill; arrow shows location on DEM; (d) photo looking updip along profile in c. Note tilted sidewalk slabs along scarp face.
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