The San Francisco Earthquake 



295 



severely, the principal buildings at Stan- 

 ford University being destroyed or badly 

 injured and San Jose being partly ruined. 

 It is noteworthy, as indicating the nar- 

 rowness of the general zone of destruc- 

 tion, that the Lick Observatory, situated 

 on Mount Hamilton, about 15 miles east 

 of San Jose, was uninjured. The district 

 drained by the Pajaro River, between the 

 town of Hollister and Monterey Bay, was 

 much disturbed. The railroad for dis- 

 tances up to a mile was depressed from 4 

 to 6 feet. Between Castroville and Mon- 

 terey the ground is said to have opened 

 and shut and mud to have spurted from 

 the fissures. 



In the immediate vicinity of the coast 

 •comparatively little damage is reported, 

 although the lighthouse at Point Arena, 

 which, as already noted, is on the line of 

 the San Bruno fault, was destroyed. 



THE EARTHQUAKE ZONE 



The general zone of destruction cor- 

 responds very closely to that of most of 

 the earthquakes of central California. 

 With the exception of the Vacaville 

 •earthquake in 1892, which was most 

 severely felt in a belt stretching from 

 San Francisco northeasterly through the 

 opening in the Coast Range near Mar- 

 tinez and across the Great Valley to the 

 lower slopes of the Sierra Nevada, most 

 of the severe shocks have manifested 

 themselves along the zone stretching 

 from Ukiah to Hollister and Salinas. In 

 -other words, their major effects are con- 

 fined to a zone at least 200 miles in length 

 .and approximately 30 miles in width. 

 The distribution of intensities along this 

 zone, as illustrated by the destructive 

 effects at San Jose and at Santa Rosa, 

 points decidedly to the initiation of the 

 disturbance from a line or plane rather 

 than from a point or definite centrum. 

 Furthermore, the general parallelism of 

 this line or plane with the great -faults of 

 the region can, in the light of geological 

 history, scarcely be considered a mere 

 coincidence. In short, the conclusion 

 that the recent San Francisco earthquake, 

 like those which have previously shaken 



the city, was of tectonic origin and that it 

 was due to movement along one or more 

 of the great faults may be regarded as 

 reasonably certain. Whether this move- 

 ment was along the San Bruno fault or 

 along some other dislocation yet to be 

 traced by patient geological work, cannot 

 be determined from the crude and meager 

 data now available. The reported de- 

 struction of the Point Arena lighthouse 

 suggests that the San Bruno fault may 

 have participated in the disturbance. If 

 so, careful observation and comparisons 

 of levels in the vicinity of San Francisco 

 Bay may discover the extent of the move- 

 ment. 



EXPLANATION OE ABSENCE OF TIDAL 

 WAVES 



It is very probable that faults parallel 

 with those known on land traverse the 

 sea bottom along the coast. If any con- 

 siderable throw has taken place along 

 such a submerged fault, we may expect 

 to receive indication of the event in a dis- 

 turbance of the tidal records. Although 

 in 1856, after a severe shock, lasting 8 

 seconds, the waters of San Francicso Bay 

 are said to have risen, to have maintained 

 their level for 5 minutes, and then to have 

 fallen 2 feet below their ordinary stage, 

 noticeable "tidal waves'' do not appear 

 to be characteristic of the earthquakes in 

 California, and this fact indicates either 

 that the shocks originate in the land area 

 or else that they are caused by displace- 

 ments of slight throw. 



That San Francisco will rise beauti- 

 ful and triumphant from ruin no one who 

 knows California can doubt. Earth- 

 quakes are a risk that will be accepted by 

 the people in the future with as little 

 hesitation as in the past. They had grown 

 a little careless and were taken unawares 

 by the fatal combination of circumstances 

 that made fire a more ruthless enemv 

 than earthquake. Shocks will visit the 

 new city, but they will shake buildings 

 better able to resist them and less com- 

 bustible. Professor Holden, writing in 

 1896, remarked that "the earthquakes of 

 a whole century in California have been 



