364 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION. 
of movement in the first-mentioned directions and in those opposite seems to be best 
in the case of foundations, since loose articles may often have been thrown in the direc- 
tion of an earthquake thrust, while houses moved opposite to it. ‘The supposition is 
that houses usually shifted opposite to the thrust. Furthermore, it must be borne in 
mind that the contents of a building may be influenced by the movement of the building, 
rather than by the direct earthquake thrust itself, and thus give results pointing in the 
opposite direction. 
Cause of shifting. — From the fact that northwest and southwest displacements were 
of most frequent occurrence, it seems likely that the main earthquake moyements were 
southeast and northeast. 
The fault which is believed to have caused the earthquake runs in a direction about 
N. 40° W., and passes within 3 miles of San Mateo. It will be noted that the dominant 
directions of movement were parallel and at right angles to the fault-line. 
Evidence appears to show that in any one direction there was a succession of thrusts. 
In one instance, a bureau was jerked by successive small movements a distance of 6 feet 
toward the northwest. The course of such moving objects can often be traced by the 
marks left in dust. Some objects that were moved had returned to their original posi- 
tion when the end of the shock came. 
Relative intensity of the main movement. — Considering only the northeast-southwest 
directions and those at right angles to them, we find that of all the houses that moved 
on their foundations, 31 per cent shifted southwest and northeast, and 27 per cent north- 
west and southeast. (See table on page 359.) 
Of the chimneys that fell obliquely or upward with reference to the slope of the roof 
or that jumped or shifted, which gave the most trustworthy evidence in cases of falling 
chimneys, 22 per cent moved southwest and northeast, and 19 per cent northwest and 
southeast. The figures for all the chimneys give the predominance to movements in 
the northwest and southeast directions, but this fact is not significant, since the majority 
of roofs sloped in those directions. 
Among the cases of liquids spilt, the southwest-northeast movement was greatly 
in excess of that northwest and southeast, 51 per cent of the total spilling in the former 
ways, and 34 per cent in the latter. 
In addition to the evidence of the figures in other tables, that given in the table on 
page 361 may be cited. Forty-seven per cent of the dishes and similar articles went 
southwest and northeast, while 42 per cent went northwest and southeast. The same 
fact is indicated by the dishes that faced in these directions and did not fall.  Fifty- 
eight per cent of the cases in which dishes remained standing on the shelves, when 
they were at liberty to fall in one or more of these ways, were cases in which they 
failed to fall northwest or southeast. According to the table on page 362, in 49 per cent 
of the cases of furniture movement the direction taken was either southwest or north- 
east, or both; whereas it was northwest or southeast in only 30 per cent of such 
cases. 
The following table enumerates the cases in which houses moved a distance of more 
than 0.25 inch on their foundations; in other words, the worst cases of the kind. It 
gives the sum of the distances moved in each direction. 
Among the most serious shifts, those to the southwest predominate slightly in number 
and distance over the northwest ones, but owing to the excess of southeast movements 
over those to the northeast the percentages for the combined opposite movements are 
just the same — 37 per cent in each case. Numerous houses shifted both southwest 
and northwest, but different distances each way. In exactly half of the cases the move- 
ment southwest was greater, and in the other half that of the northwest movement was 
in excess, while the average distance moved either way was the same. 
