Latitude: N 36°17'42"
Longitude: W 120°52'30"
Number of Bench marks: 49
Number of Surveys to 2000: 5
Date of Initial Survey: 31 July 1985
Date of Latest Survey: 1 July 1993
Trespass Permission: Level line is on a private ranch. Permission to trespass is reqired
From King City, proceed east-southeast 14 miles on Lonoak Road to its intersection with Hwy 25; tu rn left and proceed east-northeast about 3 miles to the Lewis Creek Road; turn right and proceed 2.8 miles to the Rist Ranch. Lewis Creek forms the county line in this vicinity between Monterey and San Benito counties.
This line follows the floor of Lewis Creek across the San Andreas fault 3.5 miles east of Lonoak, on the San Benito-Monterey County line. Several of the bench marks are considered as little more than temporary, because they are in rather small boulders th at may be dislodged during a flood. Many bench marks in this line were obliterated in the flood of 1993 and have not been replaced.
Four levelings are graphed in an accompanying figure; four bench marks on the east side of the fault have risen about 10 mm relative to those on the west side of the fault, for a rate of 2 mm/yr. Except for bench mark LC32, one may infer that the east block is tilting slightly to the east as well. I conclude that a tectonic wedge perhaps 200m wide is rising relative to the remainer of the land. The horizontal creep in this segment of the fault is nearly 30 mm/yr. (Burford and Harsh, 1980).
Burford, R.O. and P.W. Harsh, 1980. Slip on the San Andreas fault from alignment array surveys. Seismological Society of America Bulletin 70, 1233-1262.
Sylvester, A. G., 1995. Nearfield vertical displacement in the creeping segment of the San Andreas fault, central California, 1975 to 1994. Tectonophysics 247, 25-47.
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