GENER-^LIZATIONS CONCERNING EARTHQUAKES 61 



and since we cannot depend on an accuracy in geo- 

 graphic positions of much more than one part in 150,- 

 000, it is seen that a change of one foot in 30 miles is 

 most hkely due to errors of triangulation. This would 

 mean that, in 150 miles, a change of four or five feet 

 would probably be due to errors of triangulation. The 

 new position of Gaviota is four and one-half feet ap- 

 proximately southeast by east from the old one. 



The change in direction and amount of the new geo- 

 graphic positions from the old ones, resulting from the 

 latest adjustment, from what occurred when the pre- 

 liminary computations were made a few years ago, has 

 not been thoroughly analyzed by this office. This will 

 be done in the immediate future and it is hoped that 

 a publication setting forth the results will be shortly 

 forthcoming. In any event, the latest results seem to 

 indicate that the changes in position (reported on in 

 special pubKcation No. 106, "Earth Movements in Cali- 

 fornia," a copy of which is enclosed) were due to tri- 

 angulation errors and not actual earth movements, ex- 

 cept for some of the stations. I have in mind the ones 

 to the southward of Mt. Toro and Santa Ana, where 

 there seems to have been a progressive movement to 

 the northeastward. 



As soon as we have anything more definite than 

 what is given above, I shall communicate with you 



further. 



Very truly yours, 



(Signed) R. L. FARIS, 



Acting Director. 



A possible ambiguity in the next to the last para- 

 graph from which it might be inferred that the moun- 

 tains south of El Toro and Santa Ana had moved 



