The recent rapid growth of earthquake investigation in the United States has been largely due to economic reasons and especially to the realization by engineers and architects that, with increased knowledge of earthquakes, much can be done to prevent loss of life and damage to property through better design of structures. The inevitable result has been a broadening of interest of seismologists and geologists, and the latter are giving more attention to earthquakes than in the past.
It must not be inferred that the geologists of the United States have neglected earthquakes. Not only have they investigated in the field all the more important ones in which there has been surface geologic change, but they have studied the lesser earthquakes, especially in California and New England. Probably the most important contribution to the determination of the immediate cause of earthquakes is the elastic rebound theory of Harry Fielding Reid . . .