Geophysical Mapping of the Hockley Fault in Northwestern Houston and Recent Surface Observations
Environmental Geophysics Associates, 2000 Cullen Ave., Ste. 7, Austin, Texas 78757
Active growth faults cutting the land surface in the Gulf Coast area represent a serious geohazard. Considering the average movement of these faults is a few inches per decade, the potential is high for structural damage to highways, industrial buildings, residential houses and railroads that cross these features.
Common methods used to identify these faults include: the analysis of aerial photographs and field mapping; borehole data on both the down- and upthrown sides of the faults; core data; and familiar geophysical methods such as resistivity, gravity, magnetic, conductivity, ground penetrating radar, and gravity. A pioneering resistivity investigation was done over some of the Houston faults by Kreitler and McKalips (1978). Field mapping and analysis of aerial photographs are the most frequently used methods for locating faults in the Gulf Coast area. Geophysical methods are sporadically used to estimate the locations and parameters of these faults. Opinions concerning the effectiveness of these geophysical surveys are mixed, and geophysical techniques are not generally recognized as primary tools in engineering-scale fault studies.
However, remarkable advances in the manufacturing of geophysical instruments over the last ten years have made geophysics a viable tool for engineering studies of these faults. Data quality has increased with the advent of continuous data collection. The data are better processed and are interpreted by new and improved software packages that result in improved subsurface imaging and mapping. This article describes an integrated geophysical survey using ground penetrating radar (GPR) and resistivity imaging methods over the Hockley Fault in the northwest part of Houston, Texas. Results indicate that both methods successfully imaged significant anomalies across the known fault location.
AAPG Search and Discovery Article #90158©2012 GCAGS and GC-SEPM 6nd Annual Convention, Austin, Texas, 21-24 October 2012