COMPARISON WITH OTHER SEVERE EARTHQUAKES IN THE SAME REGION, 

THE EARTHQUAKE OF 1868. 
The earthquake of October 21, 1868, was most severely felt in the region about San 
Francisco Bay, particularly on the east side in the vicinity of Haywards. The time 
of its occurrence is variously stated from 7° 47" to 7" 54" a.m. It gave rise to disasters 
in the city of San Francisco, and some people recalling the event vividly are of the opinion 
that the shock was as severe as that of April 18, 1906. Early in the investigation of 
the latter earthquake, it became apparent that the relationship of the two earthquakes 
would be an essential part of the inquiry. Shortly after the earthquake of 1868 a com- 
mittee of scientific men undertook the collection of data concerning the effects of the 
shock, but their report was never published nor can any trace of it be found, altho 
some of the members of the committee are still living. It is stated that the report was 
supprest by the authorities, thru the fear that its publication would damage the 
reputation of the city. Our knowledge of that earthquake is therefore not very full, 
and is contained chiefly in the newspaper reports of that day. A summary of this data 
is given in Holden’s Catalogue of Earthquakes,’ and by Griesbach.? 
With the object of supplementing the facts regarding the earthquake of 1868 recorded 
by Holden, for the purpose of comparing it with that of 1906, an inquiry was started 
and intrusted to Mr. A. A. Bullock. ‘This gentleman has reviewed the periodicals of the 
time, and has interviewed many people who experienced the shock. He has also ex- 
amined the region of maximum intensity, and has had, on several of his trips, the guid- 
ance of old residents. In response to a request by the Commission, several people 
have written an account of their experiences at the time of the earthquake of 1868. In 
this way a considerable body of valuable information has been gotten together, which 
supplements to an important degree the extant accounts of that earthquake. 
THE FAULT-TRACE. 
It appears from Mr. Bullock’s inquiries that the earthquake of 1868 was due to an 
earth-movement along the base of the hills which overlook San Francisco Bay on the 
east, and which are often referred to, particularly farther north, as the Berkeley Hills. 
These hills present a remarkably even, straight front, and without doubt represent 
a degraded fault-scarp. Along the base of this scarp a crack opened on the morning 
of October 21, 1868. This crack is regarded as the trace of the fault which caused the 
earthquake. Its position has been determined at intervals along a nearly straight line 
from the vicinity of Mills College, east of Oakland, to the vicinity of Warm Springs near 
the Santa Clara County line; but the evidence of its existence to the northward of San 
Leandro is not very satisfactory. The county was then unsettled, and the information 
consisted of reports of cow-boys riding the range. From San Leandro southeastward, 
however, the evidence is full and conclusive. The general trend of the fault is north- 
west-southeast; or, to be more exact, N. 37° W., a bearing almost the same as that of 
——hs 

: Smithsonian Misc. Coll., vol. xxxvii, 1898. 
? Mitt. d. k. k. Geograph. Gesellsch. in Wien, Band xii, 1869, pp. 223-231. 
434 
