. Land-surface - Subsidence Active - Faulting in the Coastal Presented to

LAND-SURFACE SUBSIDENCE AND ACTIVE FAULTING IN THE TEXAS COASTAL ZONE Land-Surface Subsidence Land-surface subsidence characterizes much of the Texas Coastal Zone, but is most common in the upper part of the Zone and especially in the greater Houston area. [...] A number of factors can result in surface < subsidence of land; however, the major ~ause in affected portions of the Texas Coastal Zone is the lowering of pressure heads due to the withdrawal of ground water. [...] The amount of clay beds in the section affected by pressure decline is thus a factor in determining the amount of clays that will undergo volume reduction and hence the amount of land- surface subsidence that will occur. [...] The amount of piezometric decline and the amount of resulting land-surface subsi- dence is not directly a function of the total amount of w-ater with- drawn, but rather of the concentration of wells, pumpage, and sub- surface geology. [...] In the past the people of Houston-Galveston area have generally been unaware of the presence of active faults.