100 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION. 
About 125 yards below the dam the fault past thru the lower end of a massively built 
brick and cement waste weir tunnel. The inside diameter of the tunnel was about 7 
or 8 feet and the walls were 17 inches thick. At the intersection of the fault within this 
structure, the latter was stove in and smashed in pieces for a distance of about 28 feet. 
The tunnel was offset about 5 feet. In the shattering of the brick work, the cracks and 
ruptures in no case followed the cement between the bricks, but broke across the latter; 
the cement and its adhesion to the bricks being stronger than the bricks themselves, 
altho the bricks were evidently carefully selected and of good quality. Several cracks 
traversed the tunnel longitudinally and obliquely to the northeast of the part that was 
demolished. (See fig. 36.) 
- About 550 yards below the San Andreas dam, the fault-trace crost a boundary fence 
. between the estate of D. O. Mills 
and the property of the Spring 
Valley Water Company, causing an 
offset of about 10 feet. Here the 
deformation of the fence was dis- 
tributed over a zone 300 feet wide 
in the direction of the fence, or 
about 250 feet in a direction nor- 
mal to the trace of the fault. A 
survey of the dislocated fence 
made by R. B. Symington, C.E., is 
shown in fig. 87. Half a mile be- 
low the dam, the fault again crost 
the Pilarcitos pipe. A note by 
Mr. Anderson as to the conditions 
at this intersection is as follows : 
It is a 2-foot pipe made of iron 
linch thick. The fault broke it at 
an upward bend. An elbow at the 
1000 feet bend was crusht by the compression 
and thrown down, while the two 
remaining ends were brought about 
22 inches nearer together. At the 
same time they were faulted past 
each other a distance of 20 inches. 
The pipe runs N. 25° E., making an angle of 65° with the fracture, which here runs N. 
40° W. The telescoping at this angle, being 22 inches, represents 52 inches of faulting. 
Scale along fence line 
) 500 
Scale normal to fence line : 
9 10 20 feet 

Fia. 37.— Fence B of fig. 80. Dislocated by fault. 
In this neighborhood the fault crost a wire fence nearly normally, the line of which 
had been carefully established by a series of stone monuments. The fence marks the 
boundary between the estates of D. O. Mills and A. M. Easton. The deformation of the 
fence as shown in the accompanying diagram, fig. 38, from a survey by R. B. Syming- 
ton, C.E., extended over a zone at least 2,200 feet wide. On the southwest side of the 
fault-trace, the fence was displaced to the northwest a distance of 9.3 feet, and on the 
northeast side it was displaced to the southeast 3.4 feet, making a total displacement of 
12.7 feet and showing a slight drag close to the line of the fault. There were two par- 
allel cracks representing the fault about 90 feet apart, and the chief displacement took 
place on the west crack. 
About 0.625 mile farther southeast, near the upper end of Crystal Springs Lake, the 
fault crost another fence showing a displacement of 9 feet. About 0.25 mile south- 
east of this place, the fault crost the Locks Creek 44-inch pipe line. Regarding this 
intersection Mr. Anderson writes: 
