GENERALIZATIONS CONCERNING EARTHQUAKES 13 



have hardly entered into an understanding of the 

 subject. 



A laboratorty of this kind is being erected 

 at Pasadena by the Carnegie Institute of Washington 

 and equipment is being installed. Much essential in- 

 formation now lacking concerning the quakes of South- 

 ern California will be acquired there during the coming 

 years, under the able guidance of a most competent 

 director, Dr. H. 0. Wood. Seismographs are also 

 located at Leland Stanford University and the Uni- 

 versity of California at Berkeley, and a concerted 

 scientific effort is being made to supply the present 

 deficiencies of knowledge of local earth movements. 



The savants of that most unfortunately earthquake- 

 afflicted country of Japan have been leaders in seis- 

 mologic research, and it is to them that we owe a large 

 part of our knowledge of the phenomena. 



OCCURRENCE OF EARTHQUAKES 



Movements of the entire crust of the earth are tak- 

 ing place constantly at all times. Its surface heaves 

 up and down slowly, sometimes from uplifts that are 

 nearly uniform over large areas and, again, along 

 narrow belts of folding and faulting. Some parts are 

 rising and others sinking. Nowhere on earth are there 

 more perfect records of such movements of past geo- 

 logic times as in the rock structure of Southern Cali- 

 fornia. 



Earthquakes are usually associated with regions of 

 late mountain-making. There are two great zones of 

 younger mountain ranges. One of these circumscribes 

 the sunken Pacific Basin, including the west coast of 

 North and South America, New Zealand and New 



