174 W. H. HOBBS REPEATING PATTERNS IN STRUCTURE OF LAND 



MILES 



Figure 44. — Changes of Throw 

 measured on the Course of a 

 Fault near the Shore of Bus- 

 sell Fjord, Alaska 



This fault opened in September, 

 1899, (After Tarr and Martin) 



Kaigenko, it was the south limb which was 

 downthrown and by approximately the 

 same amount.^® 



The same holds true of the faults of the 

 Owens Valley, California, either opened or 

 increased, during the great earthquake of 

 1872. At a point a mile south and a little 

 east from Diaz Lake, as is shown by the 

 beautiful maps and views prepared by 

 Johnson,*^ the vertical downthrow here 

 changes most abruptly from the eastern to 

 the western limb of the fault. 



Two additional instances may be cited 

 which especially well illustrate the abrupt 

 changes in vertical throw on earthquake 

 faults. The Chedrang fault, opened in 

 Assam during the great earthquake of 1897, 

 offers one of the grandest examples of an 

 earthquake fault that has thus far been 

 studied. The throws, measured in feet, 

 here uniformly applying to the upthrown 

 limb, are given after Oldham^^ on the map 

 reproduced in figure 43. As one goes 

 from north to south along the course of the 

 fault the displacements, measured in feet, 

 read in order: 32, 0, 18, 35, 0, 8, 25, 12, 

 8, 2, 0. 



Perhaps even more interesting and sig- 

 nificant are the throws on the fault which 

 was opened near the shoreline of Eussell 

 Fjord, Alaska, in September, 1899 ; since 

 here the cross-valleys seem to represent 

 roughly the dividing lines between consecu- 

 tive fault blocks (see figure 44).^® 



^ Omdri : Preliminary note on the Formosa earthquake of March 17, 1906. Bulletin 

 E. I. C, vol. 1, No. 2, pi. 17. 



^ The earthquake or 1872 in the Owens Valley, California. Beitrage zur Geophyslk, 

 vol. 10, 1910, pp. 378-379, pi. 17b. 



88 R. D. Oldham : Report on the great earthquake of June 12, 1897. Memoirs of the 

 Geological Survey of India, vol. 30, pi. 42. 



89 Tarr and Martin : Recent changes of level in the Yakutat Bay region, Alaska. 

 Bulletin of the Geological Society of America, vol. 17, 1906, pp. 50-64, pi. 23, fig. on 

 p. 63. 



