Abstract: Active Surface Faulting, Texas Coastal Zone

C. W. Kreitler

Surface faulting in the Texas coastal zone is the result of natural activation of subsurface faults, originating in the Tertiary section, and of man-induced activation from extensive ground-water withdrawal and subsequent decline of the piezometric surface. Several lines of evidence indicate that widespread surface faulting has occurred by natural activation in the Quaternary. The extrapolation of subsurface Tertiary faults to land surfaces is coincident with active surface faults, aerial photographic lineations, rectilinear-drainage patterns and growth faults in the shallow Pleistocene Alta Loma sand. Topographic escarpments coincident with active faults in the Houston area existed before major ground-water withdrawals.

However, ground-water withdrawal is the primary mechanism for fault activation in Harris and Galveston Counties. The faults probably are partial hydrologic barriers causing differential consolidation of the shallow aquifers. Data from tiltmeters across active faults show that vertical movement is coincident with piezometric-surface declines. Surface faults which appear to be up-to-the-coast faults have subsurface equivalents that dip down to the coast. Subsidence profiles across active faults and surface traces of extrapolated faults commonly show increased subsidence on the upthrown side or on both the upthrown and the downthrown side with the fault remaining in a zone of minimal subsidence.

AAPG Search and Discovery Article #90972©1976 AAPG-SEPM Annual Convention and Exhibition, New Orleans, LA