Surface Deformation Analysis of the Houston Area: Investigating Contributions of Faults, Salt Domes, and Major Storms

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2019-08

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Abstract

The Houston area has undergone significant ground deformation in the last century, with the main factor being attributed to groundwater/natural gas withdrawal. However, subsidence can be due to groundwater withdrawal or excess loading brought about by heavy precipitation. Houston has recently been subjected to multiple flooding events which appear to be increasing in frequency. The Houston area is also home to faults and salt domes that contribute to surface deformation. The effect that these factors have had on ground deformation has not previously been studied; certain components of ground motion have been misinterpreted, or largely ignored in scientific studies and when making policies. In this study we investigate the contributions of surface and groundwater to subsidence using data collected over the past 30 years to model/predict groundwater fluctuations and look at the correlation with faults/salt domes and GPS data to see how surface deformation patterns have changed in recent years. The high rate of salt motion coupled with CO2 injection has resulted in uplift in southern Harris County, which acts to alleviate groundwater/gas withdrawal induced subsidence. Observed fault motion along the Long Point-Eureka Heights system is correlated with groundwater trends from 2006-20107. The northern Houston area shows strong subsidence of up to 16 mm/yr and an elongated subsidence bowl. The weakened aquifer systems in the north and southwest are more susceptible to intense subsidence and major flooding. These trends may be matched in the Woodlands and southwest Harris County in the future.

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Keywords

Houston, Subsidence, Hurricane Harvey, Hurricanes, GPS, Radar, Salt domes, Flood management, Flood events, Seismic faults

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