THE EARTH MOVEMENT ON THE FAULT OF APRIL 18, 1906. 101 
Just above the northern end of Crystal Springs Lake, a 44-inch water main made of 
iron 0.125 inch thick runs up the hill from the lake valley in a direction about N. 28° E. 
This line is buried all the way under several feet of soil. The fault crosses it at the base of 
the hill, in its N. 37° W. course, thus making an acute angle of 65° with the pipe line. 
At the intersection of the fault and the pipe line, the heavy rivets of the pipe were torn out 
all the way around at a section joint and the two sections were jammed into one another a 
distance of 4 feet 4 inches. In addition to the telescoping of this pipe, a slight change in 
course was induced, so that the northeast end trended one or two degrees more toward the 
east than the other end. This was shown by the fact that the broken ends did not fit into 
each other squarely. There was no lateral displacement, the whole movement having been 
taken up by the telescoping, but there was a bending of the pipes at the point of the break, 
as mentioned. The main part of the pipe, at a distance from the fault, must have moved 
with the land. At the fault-trace there was a bend amounting to one or two degrees. 
Supposing the bowing to be simple, this amount indicated that the land must have carried 
the pipe the distance represented by the telescoping, or about 10 feet, within 300 to 500 feet 

Scale along fence line 
sooo feet 
Lae 8 BOSS, AE RS 
Scale norma! to fence line 
10 2ofeet 
Fig. 38.— Fence A of fig. 30. Dislocated by fault. 
of the fault on one side, and that beyond such a point the pipe must have preserved its 
normal course. Asa matter of fact, this same pipe was broken on the northeast side of the 
fault about 400 feet further up the hill. The break occurred at the junction of 2 sections, 
the rivets having been sheared off and part of the rim torn away at the rivet holes. The 
ends were pulled apart 3.375 inches. Here the pipe resumed its former course, but. owing 
to the slight amount of the pipe displayed by the excavation, it was impossible to see 
whether a return bend occurred or not. Beyond the break the direction was as before 
measured, approximately N. 28° E. No such break occurred on the southwest side of the 
fault. A crack was formed in the earth at right angles to the pipe for several yards o 
either side of the break. 
_ The measurements of the engineers of the Spring Valley Water Company on the 
break and displacement of this pipe at the intersection above described by Mr. Ander- 
son are given in the accompanying diagram, fig. 39. 
About a mile southeast of the Locks Creek pipe line, the trace of the fault entered 
Crystal Springs Lake for the stage of water of April, 1906. At 2.5 miles farther 
