46 SOUTHERN CALIFORNIA GEOLOGY 



releases of strain along fault lines. Seismologists have 

 been strenuously striving to ascertain methods for pre- 

 dicting the place and time of future earthquakes with 

 a hope that laws of periodicity of recurrences of shocks 

 along fault lines might be established in countries 

 where they have been more sufficiently studied, as 

 in Japan or Italy. The best authorities agree, how- 

 ever, that such methods have not been perfected, and 

 that such advance along these lines as has been accom- 

 plished, required the accumulation of more and better 

 data than we have acquired in the past in California. 



OPINIONS OF OTHERS 



Milne has said, "Ability to herald the approach of 

 these calamities would unquestionably be an inestim- 

 able boon to all who dwell in earthquake-shaken coun- 

 tries, and the attempts which have been made both 

 here and in other places are extremely laudable." 



Dr. Daly has truly said^ that "fairly elaborate plans 

 are already worked out for measuring earth strain 

 which develops as the years go on. It may take a 

 generation or more to accumulate sufficient data for 

 the purpose of forecasting the place and, less probably, 

 the time of earthquakes." Arrangements are now 

 being installed for such measurements in California. 



It is true that earthquake centers may have mi- 

 grated from time to time, as in Italy, along the lines 

 of a great fracture where they occur, and that some 

 students of earthquakes in countries long under ob- 

 servation have concluded that there are periods of 

 maximum occurrences of shocks along certain given 



'Our Mobile Eai-th, 1927. 



