A Geophysical Study of Active Faulting in Fort Bend County, Texas

Several active faults are reported from southeast Texas. These faults have been studied in great detail in Harris County, but little work has been done in Fort Bend County where there are at least four known fault systems. These are the Long Point, Needville, Arcola, and the Addicks fault systems. This study focuses on the Needville and Arcola fault systems in an effort to determine the continuity and displacement along these two fault systems. The purpose of this study is to build on the previous work with the use of the latest tools to identify and understand the faulting mechanisms in the Fort Bend County. This study used Light Detection and Ranging (LiDAR), aerial photographs, Ground Penetrating Radar (GPR), 2D Seismic, Global Positioning System (GPS), gravity, and well logs which proved to be complementary, and work very efficiently together. The LiDAR produced a comprehensive surface model that revealed four faults never reported before, and extended previously recognized faults. The GPR data show disturbance in the fault zone, and provided a link of LiDAR to 2D Seismic data. The 2D Seismic stacked profile displayed a comprehensive vertical section that allowed the Needville Fault to be interpreted to approximately 800 meters. The Well logs provided a source of information to produce a subsurface model that helped identification of the fault locations. The gravity data confirmed that there is a low gravity anomaly in the Needville Fault Zone. GPS suggested movement of 9 cm over 4 years for the Arcola Fault. All these complementary datasets helped create a comprehensive 3D model that demonstrates complex geology in this passive margin of the Gulf Coast.