UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 6, No. 19, pp. 413-444 Issued December 21, 1911 



THE ELASTIC-REBOUND THEORY OF 

 EARTHQUAKES* 



BY 



HAERY FIELDING RE ID 



Earthquake shocks have apparently occurred in all geologic 

 ages, in the past as well as in the present. This is shown by 

 the presence in the rocks of sandstone dykes, which have been 

 explained as the filling up of earthquake cracks from above or 

 below by loose sand, which afterwards became consolidated ; and 

 by the presence of faults, which is, in itself, evidence that shocks 

 occurred when they were formed ; for whenever there is a 

 movement on a fault surface, it is always accompanied by an 

 earthquake. 



It is very easy to picture to ourselves the terrorizing effect of 

 an earthquake shock to an uncivilized people; but the lack of 

 records in prehistoric times, and even later among uncivilized 

 people, accounts for the fact that the history of many serious 

 and disastrous earthquakes has been wholly lost. Indeed, with 

 the exception of a few countries, such as Japan and China, it 

 is only within the most recent times that a complete record of 

 the heavy shocks occurring in civilized regions has been kept ; 

 and, without doubt, many serious shocks in less known parts of 

 the world's surface, even within the last two or three hundred 

 years, have entirely escaped our notice. At the present time 

 fairly complete lists of even the weaker shocks are kept. 



* First of the Hitchcock Lectures delivered at the University of Cailfor- 

 nia in the Spring of 1911. These lectures, with additions, will be published 

 as a book. 



