SEYMOUR, DAVID, Leighton and Associates, Inc., Irvine, CA
ABSTRACT: Redevelopment of Oil Field Property and Active Faulting: A Case History: Huntington Beach Oil Field
Since the middle part of this century, oil field properties in southern California have been redeveloped for residential use. Portions of the Huntington Beach oil field located along the west-central side of Huntington Beach Mesa are currently proposed for redevelopment. The redevelopment site is transected by the active North Branch fault of the Newport-Inglewood fault zone. The North Branch fault is one of many right-lateral strike-slip faults within the Newport-Inglewood fault zone.
Recent geotechnical studies across the North Branch fault determined that the fault has ruptured during the Holocene epoch (the last 11,000 yr before present). Numerous trenches were excavated across the fault and exposed several splays offsetting late Pleistocene marine terrane and eolian deposits. Four trenches excavated at the top of a pressure ridge at the western edge of the mesa exposed offset gopher burrows (krotovina) and soil horizons. The offset krotovina and some fractures are infilled with Native American midden deposits, which have an estimated age of 5000 yr before present. The fault as exposed in the four trenches consists of a 3-8-ft-wide zone of fractures with apparent vertical offsets ranging from 3 to 8 in. In one of the trenches, the Bt soil horizon is warped, and he ped faces have been tilted approximately 70 degrees across the fault. In three trenches, a 1-3-in.-wide midden infilled fracture is located on the southwest side of the fault. Based on these features, a building setback was established along the length of the fault.
AAPG Search and
Discovery Article #90992©1993 AAPG Pacific Section Meeting, Long Beach,
California, May 5-7, 1993.