Sarabudak and Nieuwenhuise reported in 2007 that active growth faults cutting the land surface in the Gulf Coast area can represent a serious geo-hazard. Considering that the average movement of these faults can be as high as a few inches per decade, the potential exists for structural damage to highways, industrial buildings, residential houses and railroads that cross these features.
Common methods to identify these faults include mapping from aerial photographs and field work; subsurface borehole data (on both the down- and upthrown sides of the faults) including geophysical logs, core and other borehole data; and geophysical surveys including gravity, magnetics, resistivity and conductivity. Historically, the geophysical techniques have not been widely used in engineering-scale fault studies because of concerns about their effectiveness. However, in the past 10 years advances in the quality of the geophysical instruments and consequently the quality of the data produced have made geophysical methods viable tools for characterizing these faults.
Data quality has been significantly improved by the advent of continuous data collection. More advanced software has improved data processing, leading to
better subsurface imaging and interpretation. To test the ability of geophysical techniques to characterize faults, we designed an integrated geophysical survey using ground penetrating radar (GPR), resistivity imaging, magnetics and micro-gravity over the Hockley and Willow Creek faults located in northwestern Houston, Texas. Results of this investigation indicate that all methods successfully imaged significant mappable anomalies across the known fault locations.
Introduction
The coastal plain of the Gulf of Mexico (GOM) is underlain by a thick sequence of largely unconsolidated, lenticular deposits of clays and sands (Kasmarek and Strom, 2002). Growth faults are common throughout these sediments. Based on a study of borehole logs and seismic reflection data, many of the larger of these faults have been mapped to depths of 3,000 feet to 12,000 feet below the surface (Kasmarek and Strom, 2002). Most of these faults are associated with natural geologic processes such as differential compaction and salt movement and many have been active since the Cretaceous. Some of these faults, distributed throughout the coastal plain of the GOM, are currently active and disturb the ground surface (Clanton and Verbeek, 1981).
The Houston area has a very active shallow fault system, as evidenced by surface movement and measurable localized subsidence (Verbeek and Clanton, 1981). Evidence of faulting is visible from structural damage such as fractures and displacement of the ground surface. Fault displacement is predominantly
normal, dip-slip and listric, with most growth faults south-dipping (synthetic) and some north-dipping (antithetic). Some faults are clearly active today and
disrupt the surface, causing damage to streets and creating scarps across lots, fields and streets.
The faults that are active today can be the source of damage to pavements, utilities, homes, businesses and other man-made structures in the Gulf region. In the Houston area alone (Harris County), there are more than 300 active or potentially active faults totaling over 300 miles in length (Clanton and Verbeek, 1981). These faults are often zones of sheared ground tens of meters wide rather than discrete breaks in the surface.
This paper presents and evaluates the use of four noninvasive geophysical methods for imaging the Willow Creek growth fault that cuts across Highway 249 in the northwest Houston, Texas, area.
Also see:
1981: https://archives.datapages.com/data/hgssp/data/030/030001/28_hgs0300028.htm
2002: https://pubs.er.usgs.gov/publication/wri024022
2007: https://www.twdb.texas.gov/groundwater/models/gam/glfc_n/GLFC_N_Full_Report.pdf
2018: http://www.i2mconsultants.com/downloads/corp/JGG-1-015.pdf
and General Google Search Results (here).
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