Vol. 6] Beid: The Elastic-Rebound Theory of Earthquakes. 443 



movement and to suggest the displacement of a block between two 

 faults ; the Sonora and Nippon earthquakes distinctly suggest 

 movements of a block, but we shall see, when we consider the 

 elevation or depression of mountain ranges, that these earth- 

 quakes may be explained satisfactorily without assuming such a 

 movement. 



In the ease of the California earthquake it would have been 

 impossible to prove that the elastic rebound gradually died out 

 with increased distance from the fault, if it had not been for the 

 successive exact surveys which were made in this region. The 

 change in the amount of displacement diminished very slowly 

 with the distance from the fault ; the difference in a distance 

 of a thousand feet in the neighborhod of the fault, where it 

 was greatest, was only about six inches. It is not surprising, 

 therefore, that the data regarding other earthquakes, where no 

 such surveys were made, are, with the exception of the Cutch 

 and "Wellington earthquakes, insiifficient to show a similar dis- 

 tribution of the earth movements. But the data in no way 

 oppose the idea ; and the positive evidence and the general 

 reasoning seem quite strong enough to establish it. 



