Latitude: N 36°11'35"
Longitude: W 120°46'12"
Length: 897.4m
Number of Bench marks: 23
Number of Surveys to 2000: 6
Date of Initial Survey: 1 August 1985
Date of Latest Survey: 2 July 1993
Trespass Permission: None needed, but the line is located in Caltrans
right-of-way.
Directions:
From San Lucas on U.S. 101 in central California, Drive 14 miles east-southeast
on Hwy 198 to Peach Tree Road. Continue across Peach Tree Road up the grade
about 3 miles to its crest. The east end of the leveling array is at the
crest of the grade, and i t continues westnorthwest and west part way down
the grade and across the San Andreas fault. The highway is heavily travelled
and surveying conditions may be hazardous.
Comments:
This line was established across the creeping section of the San Andreas
fault. The line segment between MG14 and MG15 is along a highway fill at
one end of a sag pond on the fault.
Results:
Four levelings are compared in an accompanying figure. The heights of bench
marks fluctuate +/-5 mm from 1986 to 1990. No vertical displacement is evident
across the fault.
Reference:
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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