[klotz] earthquake WAVES 41 



case the comparison of seismograms from different stations well 

 distributed about the seismic area will tell the story of what happened, 

 when it happened, how and where, as well as how much energy was 

 released in the adjustment. 



It is believed that there is already a great deal of material on hand 

 in the form of seismograms that if brought together and dealt with by 

 a master hand would reveal much of the interior of the earth, would 

 furnish us material for improving and extending our tables and 

 velocity curves, so that we would reach the stage of detecting along 

 certain paths of the seismic rays anomalies in density, elasticity and 

 rigidity, thereby extending a helping hand to the investigator of 

 gravity anomalies. At present co-ordination and collaboration are 

 required. 



It may be pointed out there is a check on the deduced distances 

 from various seismograms, for from them it is possible to deduce the 

 actual time of occurrence of the earthquake, which is always expressed 

 in Greenwich Mean Time, and this time we designate by the symbol 

 O. The time deduced involves of course the accurate time of a 

 station. It is not infrequent that the O's deduced from the more 

 reliable stations will agree within a few seconds, although our tables 

 for transmission times of the various seismic waves are not perfect. 

 The accordance in the determination of O for a good tectonic quake 

 is certainly very gratifying, whether the seismic convulsion be in 

 Asia, in America, or in^the depths of the Pacific. 



In closing this brief note it may be pointed out that when the 

 earthquake is one sudden breakdown from a restricted hearth then 

 the O's for all stations must theoretically be the same. But the 

 epicentre deduced from various pairs or groups of stations, when the 

 displacement occurs along a fault line of considerable extent, will then 

 not necessarily be the same, in fact cannot be the same. The P and S 

 at each station would come from the nearest part of the fault line, 

 which as we have seen was so well shown in the one of the Kurile 

 Deep. 



Seismology is slowly gaining a permanent footing in the field of 

 science, and the harvest looks most promising. 



