202 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION. 
Up the alluvial slope of Copeland Creek about 7 miles south of Santa Rosa, I found that 
chimneys were much more damaged than on the road northward from the creek to Santa 
Rosa, which usually follows the edge of the foot-hills. 
Northeast of Santa Rosa, Mr. Butler reports that along the road to the Rincon District 
the damage was very slight, as it was also on the road running northwest from Santa Rosa 
toward Fulton. ‘This road, it should be noted, keeps close to the foot-hills. 
The most severe damage in the country around Santa Rosa was found to the westward in 
the vicinity of Sebastopol. 
The great damage in Santa Rosa may be accounted for by the physiographic conditions 
and by the weakness of the buildings in many cases. The sand for mortar has usually been 
obtained from the creek and contains considerable loam. Some of the mortar seems to have 
been made with good sand and with cement. The old bank building, just west of the court- 
house, stands alone in that part of the wrecked area, a monument to good work. Usually 
thruout the wrecked area the mortar taken from the walls is easily crumbled to incoherent 
sand by pressure of the fingers. 
(EK. C. Jones.) —Very little damage was done to the gas mains in Santa Rosa as a result 
of the earthquake, but there were several explosions in the mains during the fire which 
followed. In several cases the cast-iron mains were blown apart; and when uncovered, 
the ends were found to be separated from 1 to 3 inches, according to character of ground. 
At the generating plant the damage was principally to the brick building. The entire 
east wall fell outward, and the remaining walls were badly cracked. The columns of 
the gas-holder frames were thrown down, and the water-level in the tank was lowered 
about 6 feet. The holders were twisted out of position about 20°. 
(C. T. Wright.) —There seem to have been two distinct motions in Santa Rosa, one 
from north to south, or more properly from north 30° west to south 30° east, the other 
roughly from west to east. The former motion seems to have been noticeable over a 
larger area and probably was the more violent. There is a belt along the Northwestern 
railroad tracks in which the west-east motion was specially noticeable, as shown by 
observations at the flour mill, the woolen mills, and the cannery. West of this belt, at 
the tannery on West Sixth Street, a distinct north-south, or northwest-southeast, motion 
was indicated, while east of this belt, in the region from Washington Street to A and B 
Streets, the northwest-southeast motion was specially evident and is the predominant 
motion. At Humboldt Street it becomes somewhat confused. 
Most reports agree as to “choppy,” rotary, or up-and-down movements following the 
pronounced horizontal movement, or between successive horizontal movements. This 
suggests interference of waves. The observed phenomena might be explained by the 
passage of a series of long, very rapid northwest-southeast waves of great intensity; 
and simultaneously or immediately following the beginning of this series, a second series 
of comparatively short west-east waves. Supposing the crest of the latter to have 
reached a line in the neighborhood of Washington, A, and B Streets, and the trough of this 
series to be near the Northwestern railroad tracks when a crest of the northwest-southeast 
series swept down, the two motions would tend to neutralize each other in the neighbor- 
hood of the railroad tracks and augment each other in the other district. It may be 
supposed that after the passing of this northwest-southeast crest and before the passage 
of another, the west-east waves were specially noticeable near the railroad tracks and 
did their destructive work there. If this theory be correct, another “trough” should be 
found between Mendocino Street and the Southern Pacific railroad station. The some- 
what promiscuous directions of falling objects on Humboldt Street might indicate the 
approach to this region. To test the theory would require further observation. 
(Marvin Robinson.) — Mr. Robinson of Santa Rosa states that he was just across Fourth 
Street and north of the court-house, and that at first the dome of the court-house seemed to 
be almost over him, and a few seconds later fell directly east. The brick buildings near 
him all fell east. He believes the street to have been vibrating in a vertical direction at 
the close. 
