Latitude: N 35°27'55"
Longitude: W 119°00'20"
UTM: 11 S 0316477, 3926224
NAD1927
Length: 1306m
Number of Bench marks: 106
Number of Surveys to 2006: 6
Date of Latest Survey: 29 June 1995
Date of Initial Survey: 19 August 1986
Trespass Permission: Permission to trespass is required.
Directions:
From Gorman take I-5 North to 99 North, thence to Bakersfield. Go right onto
California Street or use 178 east. Go to Chester and turn left. Proceed north
to China Grade Loop and turn right. Proceed east about one mile, then turn left
into the Chevron-Texaco Gate, and follow Kern Road (north). Turn left onto G
and W Road, then left onto Wherehouse Road. Take the first paved road right
off at Wherehouse. Then turn left off off the paved road at the base of the
transmitter tower hill. You'll be able to see the green metal shed where the
line starts.
Comments:
This box-shaped array was established two miles north of Oildale at the request
of Texaco USA to monitor the Kern Front fault which Castle and others (1983)
concluded was active. Castle and others (1983) were not able to determine with
confidence whether the fault displacement was tectonic or due to subsidence
owing to withdrawal of oil and water from the shallow reservoir, but they favored
the latter explanation.
Five levelings across the south segment of the array are compared in an accompanying
figure for the period August 1986 to June 1995. In that time, 44 mm of displacement
have occurred across the fault, for a vertical creep rate of 5 mm/yr., even
though several of the wells in the oilfield were shut-in at that time. This
rate of displacement is nearly the same rate that Nason and others (1974) found
using a tiltbeam at the same site from 1968 to 1972, after which time the tiltbeam
was stolen by vandals. A new tiltbeam was erected in November, 1986, and monitored
weekly until October 1987. It was resurrected in 2007 and is being monitored
as of 2008.
Nine of eleven short fault crossing arrays were releveled on 24 May 2007. The average rate of displacement among the arrays is 5 mm/yr over the 20 years of observations.
References:
Castle, R.O., J.P. Church, R.F. Yerkes and J.C. Manning. 1983. Historical
surface deformation near Oildale, California. U.S. Geological Survey Professional
Paper 1245, 42 p.
Nason, R.D., F.R. Philippsborn and P.A. Yamashita. 1974. Catalog of creepmeter
measurements in central California from 1968 to 1972. U.S. Geological Survey
Open File Report 74-31, 387 p.
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