The San Francisco Earthquake 



281 



Outline Map of San Francisco Bay and Vicinity. Principal known faults are 



indicated by heavy dash lines 



with a maximum throw of 20 Eeet. Prof. Four kinds of waves are generated in 



John Milne, after an exhaustive study of most earthquake shocks: (1) normal 



the scismological records of Japan, con- waves, (2) transverse waves, (3) sur- 



cluded that shocks are most frequent in face waves, and (4) epifocal waves. The 



districts that exhibit evidence of elevation first three depend upon the elasticity of 



or subsidence still in progress. the rocks traversed, are not visible, and, 



