Multidisciplinary Investigation of Surface Deformation Above Salt Domes in Houston, Texas

Surface deformation has been an ongoing problem in the Houston Metropolitan area because of the city's location in a passive margin where faulting and subsidence are common. According to previous studies the causes of the surface deformation are typically attributed to anthropogenic activities, mainly the subsurface withdrawals of oil, gas, and groundwater. However, the majority of the studies done have not accounted for the vast amount of salt underneath the Houston area and its role in the surface deformation. The objective of this study was to identify areas of surface deformation in the greater Houston area and their possible relationship with subsurface salt movements. To accomplish this, I integrated three kinds of data: 1) GPS 2) LiDAR (Airborne and TLS) and 3) Gravity. The GPS data documented substantial subsidence and uplift in the Houston area. These surface deformations may suggest continued salt withdrawal and salt diapirism. DEM derived from LiDAR documented elevation changes between areas within the salt domes and their surroundings. This could suggest salt movement, possibly the result of secondary salt withdrawal during diapirism. The changes in the gravity measurements could be another indicator of subsurface salt movements. Kriging surface displaying GPS (PAM and CORS) derived surface deformation in the greater Houston area for the years 1994 through 2010. The area is extensively covered by both CORS and PAM GPS stations. As seen in this surface there is an area of subsidence in the northwest and an area of uplift in the southeast. One key difference is the distribution of salt domes in the two areas. In the southeast there are more known salt domes relative to the northwest. This may suggest some association between uplift and salt diapirism.