GENERALIZATIONS CONCERNING EARTHQUAKES 45 



reiices throughout the length of the Hne of seismicity 

 from the Arctic Circle to near the equator, and the 

 width of the belt from the ocean depths beyond the 

 great abyssal escarpment across the Continental Shelf 

 and the Pacific and Desert sides of California into Ari- 

 zona and New Mexico. Concerning such history we 

 possess practically no data whatsoever. 



It is evident that a deduction to the effect that 

 the next great shock along the line of seismicity should 

 necessarily take place in Southern California rather 

 than at any other point along that 8,000 miles between 

 the Arctic Circle and Venezuela is preposterous. 



The present and future line of interest in earthquake 

 studies pertains to the great stresses and the elastic 

 strains resulting from them. Analysis of all of Dr. 

 Willis's writings show that he had assumed that he 

 possessed data of this kind concerning the Pacific side 

 of California which are not in existence and which 

 were both the corner stone and foundation of all his 

 predictions. 



WHY OUR EARTHQUAKES CANNOT BE 

 PREDICTED 



Two questions concerning earthquakes naturally 

 arise. These are, first, if there are laws of rythmic 

 or periodic recurrence, and secondly, if there are means 

 of predicting such occurrences. 



It is the hope and aim of every geologist that meth- 

 ods will be devised for ascertaining a manner of pre- 

 dicting the periodicy of the shocks of every earthquake 

 zone, but they have thus far not been discovered. 



We do not and cannot deny the general principles 

 of geology which hold that earthquakes result from the 



