228 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION. 
In the blocks adjacent to Point Lobos Avenue and Clement Street, between First 
Avenue and Sixteenth Avenue, in the sand-dune district, damage — mostly of Grade D — 
was prevalent. This locality is the part of the city nearest to the seat of the disturbance, 
and the cover of sand which rests upon the uneven bedrock is unevenly thick; therefore 
irregular variations of intensity are to be expected. Nevertheless it is not easy to fix the 
boundari ies between Grade C and Grade D in this part of the city. 
Along Oak and Fell Streets, and the Panhandle Parkway from Broderick Street west, 
the intensity closely approaches Grade C without seeming quite to reach it. 
Along Washington Street and its immediate vicinity, from Baker Street west to Spruce 
Street, on the crest of the sandstone ridge, the intensity is higher than for most other 
localities of exposed bedrock. Fallen chimneys and cracks in foundation walls were 
more prevalent than in most areas so situated. 
On bedrock at Point Lobos, also, the effects indicate an intensity pretty close to 
Grade C, but this locality is nearer the fault than any other Franciscan outcrop save the 
western slopes of San Bruno Mountain. 
We may say in general, therefore, that Grade D is the intensity developed on bare rock 
foundations, or on rock only moder ately coated with soil, in the northeastern part of the 
city and county of San Francisco. 
In the low lands of the valleys, and along portions of the water-front, the sand and 
alluvial deposits are thicker and the destructive effects were increased in magnitude and 
in prevalence; also thruout a large part of the sand-dune tract at the west, wherever 
evidence was obtained, increased intensity was found to prevail. 
All over Mission Valley and Hayes Valley, including Upper Hayes Valley, brick walls 
were cracked and some gables and walls actually fell. Buildings placed on weak under- 
pinning were frequently displaced slightly from the vertical. In a few cases, weak frame 
dwellings collapsed as a result of the giving way of weak foundation structures. Most 
chimney stacks were broken. In no part of this large district was evidence of this kind 
lacking, altho the majority of the structures were fairly substantial frame dwellings, and 
were of course not seriously damaged. There was much indoor damage, but no investi- 
gation of this was undertaken. 
At the outer margin of this area, marked by an intensity of Grade C, the destructive 
effects were weaker, indicating an intensity just above Grade D. Where the district 
adjoins localities which suffered a still severer shock, the damage was of greater magni- 
tude and more prevalent. Besides this gradation there were, within the limits of the dis- 
trict, several little localities where the characteristic destructive effects were conspicuously 
numerous. 
In the neighborhood of O’Farrell Street, between, say, Mason and Taylor Streets, brick 
work was sadly cracked. Photographs made before the fire (plate 874) show that some ~ 
building fronts were thrown out on O’Farrell Street in this vicinity. Many of the build- 
ings hereabouts were mediocre structures at best, but injuries were too generally dis- 
tributed to be ascribed wholly to structural weakness. The damage was not of great 
magnitude and did not indicate intensity of Grade B,so far as could be made out from the 
ruins after the fire. 
Near the City Hall there was a small locality conspicuous for the damage proatieen: 
The City Hall itself made a picturesque ruin (plates 82 and 83a), as all the world knows, 
but the character of the construction was probably a large factor in its destruction. 
Nevertheless ugly cracks in other buildings near by indicated intensity somewhat 
higher than was common in the valley district as a whole. 
Just south of Jefferson Square some weak buildings quite collapsed, and foundation 
walls were generally cracked and crusht. Wooden underpinning showed a tendency to 
lurch and throw buildings slightly out of the vertical. Similar effects prevailed along 
Folsom and Treat Streets for two or three blocks south of Eighteenth Street. 

