DIRECTIONS OF VIBRATORY MOVEMENT. 353 
themselves was no criterion of the direction of vibration of the ground except when 
these rested upon uniform foundations. Buildings upon poorly braced underpinning, 
such as are common in California, collapsed in consequence of the swaying; but the 
direction of the horizontal element in the collapse was more often determined by the 
nature of the structure than by the dominant movement of the ground. Even in ceme- 
teries the direction of overthrow of simple shafts, circular or Square in cross-section, 
failed to indicate the direction of the dominant movement, since within a small radius 
they fell to all points of the compass. The indication of the cemeteries was that the 
movement of the ground was very complex; the shafts were started swaying upon their 
pedestals, and the direction of their fall was for the most part accidental, as the rocking 
increased in violence due to the accumulating impulse. Treated statistically, however, 
the larger cemeteries afforded some indication as to the direction of the dominant move- 
ment of the ground. 
In view of what has been said, it will not be surprising that the effort to interpret the 
reports from various parts of the state regarding the direction of movement of the ground 
has been unsuccessful. The reports were in general contradictory for the same locality 
whenever there were two or more independent observers. It was evident that most 
of the reports were based on evidence of the movement of the ground which had no sig- 
nificance in isolated instances, and a general critical review of the evidence was attempted 
only by a few observers. It was also evident that in many cases the effects of one move- 
ment had imprest one observer, while the effects of a different movement had attracted 
the attention of another. In these cases the contradiction was more apparent than 
real, but there was generally doubt as to the correctness of both. Even when the reports 
were perfectly satisfactory records of facts, the latter in many cases permitted of no safe 
inference as to direction of movement except that there were several movements in 
several directions, and that the sequence of these could not be determined. 
The following report from E. G. Still of Livermore is a good example of an excellent 
account of the important facts bearing on the question of directions: 
The Railway Company’s big 20,000-gallon water-tank fell to the north-northeast. Tomb- 
stones in one graveyard fell in many directions. Lamps swung in an oval, extending about 
east and west. ‘The motion seemed to shake my bed north and south at first, then in a 
circular motion, then sideways and in every direction. Water spilt from full tanks, mostly 
on east and west sides. 
There is a suggestion here of two dominant movements — a northerly and southerly, 
and an easterly and westerly, the former being the earlier. But Mr. Crandall, for the 
same territory, reports that the general direction of motion, based on the observed spill- 
ing of liquids and swaying of suspended objects, was northwest and southeast. In 
most cases the reports consist of a statement of opinion as to the direction of movement, 
without the facts upon which the opinion is based. 
