1906.] 



SEE— THE CAUSE OF EARTHQUAKES. 

 Fig. 15. 



381 



The shattered obelisk of Mt. Pelee, photograph taken by Professor 



Angelo Heilprin, 



forces; and it is no wonder that such shaking should throw down 

 buildings, settle soft " made " ground, leaving fissures where it is 

 shaken down, and* even cause faults in the overlying mountains to 

 slip or open. 



§ 50. But the movements of faults are the effects of the earth- 

 quake^ not the cause. 



Such small slips as are usually observed would not account for 

 the enormous forces shown in the accompanying earthquakes. Be- 

 sides the horizontal form of the vibrations, so frequently shown, as 

 more fully pointed out in § 51, could not be explained by simple 



