COMPARISON WITH OTHER SEVERE EARTHQUAKES IN SAME REGION. 435 
the fault-trace of 1906 along the San Andreas Rift. The position of this fault-trace is 
shown on map 4. While in general it lies along the base of the old degraded scarp, it 
is still, for the most part, within the hill-slopes and not in the alluvium which extends 
from the base of the hills. In some places where it crost the lower ground, the crack 
showed faulting or displacement of 8 or 10 inches, but from the accounts given it is not 
clear in what direction the faulting took place. The statements indicate a slight down- 
throw on the southwest side. In other places a displacement of 3 feet is said to have 
been observed. In places the crack along the fault-trace opened to a very considerable 
depth with a width of 10 or 12 inches, and remained open until filled with falling earth. 
On the higher ground of the hill-slopes no open crack was observed; there was merely 
the trace of the rupture in the sod. This fault-trace could be followed at intervals for 
20 miles southeast from San Leandro, and it had a straight course without regard to 
the contour of the hills. In some places it was quite at the bottom of a hillside, while 
at other places it was high on the slope; and on at least one low hill it past near the 
top thru a saddle-like depression. Springs are common along the base of the hills, 
and the fault-trace was above the springs. According to the testimony of old residents 
the flow was not affected by the earth-movement.' In the hills to the northeast of the 
fault-trace, however, new springs were started and old ones revived, altho some few 
ceased flowing. 
That the crack extended down into the bedrock is testified to by many who observed 
closely. ‘Three men reported that they tried to sound the bottom of the crack, but were 
unable to do so. In the vicinity of Haywards it is reported that there were two branch 
cracks from the main one, trending off into the hills. Water and sand were ejected 
from the crack in one place. 
Between Decoto and Niles the crack left the base of the hill front, and deviating slightly 
from its general trend thus far, crost the plain of the alluvial fan of Alameda Creek at 
the mouth of Niles Canyon to the foot-hills at the town of Irvington. For the greater 
part of this distance, it appeared as an open crack. It past thru a lagoon about : 
0.5 mile in length, following closely the longer axis of the depression, and the water of 
the lagoon was drained out, apparently into the crack. At Irvington the crack became 
coincident with the very straight and even ancient fault-scarp of the foot-hills south- 
east of that town. ‘This ancient scarp has a strike of N. 38° W. Beyond this it was 
not observed farther than Aqua Caliente Creek. 
Immediately to the east of Mission San Jose, entirely within the hills, another crack 
opened with a strike of N. 18° to 20° W., which, converging upon the crack thus far 
traced, extended south as far as the county line. 
The greatest intensity of the earthquake was along the crack and in its vicinity. On 
the projection of this line southward into Santa Clara County, the intensity diminisht 
steadily as far as Morgan Hill, where it again rose. At Gilroy, Hollister, and San Juan, 
according to reports, the intensity was sufficient to throw down a few chimneys and to 
crack some brick and adobe buildings. 
The greatest damage was done at Haywards, where nearly every house was thrown 
off its foundations; while at San Leandro the shock was less severe. (See plate 144.) 
A house near old Blair Park, in the present Piedmont district of Oakland, was badly 
damaged. The only other town of that date in close proximity to the fault-trace was 
Mission San Jose, which lies in the hills a few hundred yards west of it. In this town 
were several adobe buildings, one of which, a church, was wrecked. Many chimneys 
were thrown, but the general effect was much less severe than at Haywards. 

and McCarthy, of San Leandro; Messrs. O. Hill, F. I’. Allen, F. Wrede, and H. V. Monsen of Haywards; 
Mr. Decoto, of Decoto; and Mr, W. Berry, of Niles. 
