Huang, and two co-authors, reported in 2015 that Active faults in urban areas are hazards that can cause damage to critical infrastructures. Previous works have mapped over 300 faults in Houston and surrounding areas, but many active faults remain to be found and mapped. This study locates and images faults in the highly populated medical center and university areas just south of downtown Houston.
It is challenging to identify faults in densely populated urban areas so we performed an integrated geophysical survey. This study presents data from aerial light detecting and ranging (LiDAR), two-dimensional seismic profiles, and a gravity profile to map subsurface fault segments. Gravity modeling revealed faults near the Pierce Junction Salt Dome and surrounding area. The deepest fault mapped at the cross point of the two seismic profiles dips to the southeast and the measured displacement across the fault is ~20 m.
Data from the three geophysical techniques—seismic, LiDar, and gravity—have been used to map new fault segments. The four newly-mapped fault segments provide more detailed explanation for the surface deformation of the Pierce Junction, medical center area, and downtown Houston. The seismic lines resulted in newly-mapped fault segment 1. The 2D seismic profiles show the displacement of the fault is 70 ft (~20 m) (Fig. 3). By combining the previously-mapped fault and the bending of a creek, the authors interpreted that fault segment 1 is part of the gravity driven regional fault population.
The arc of the fault is shown and the strike of the conjectured fault plane follows the trend and dip direction of other mapped faults in Houston. This may indicate that the newly recognized fault segment 1 is likely part of an existing regional fault zone. Fault segments 2, 3, and 4 are caused by salt withdrawal from the Pierce Junction Salt Dome.
Regional seismic interpretation and modeling in the greater Houston metropolitan area will help to understand the mechanism of the deep-seated subsidence. The newly-mapped fault segments hold the potential to provide an assessment of surface deformation and improve future city planning and development. The addition of new faults to the existing Houston fault maps will lead to a broader understanding of neotectonics of Houston, Texas.
[Also see "Growth Faulting and Subsidence in the Houston, Texas Area: Guide to the Origins, Relationships, Hazards, Potential Impacts and Methods of Investigation: An Update": http://www.i2mconsultants.com/downloads/corp/JGG-1-015.pdf ]
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