EARTHQUAKES IN GEOLOGY 



roar. It is difficult to stand, and at length becomes im- 

 possible to do so. People fling themselves to the ground 

 to avoid being dashed against it. The trees are seen to 

 sway violently, sometimes so much that they touch the 

 ground with their branches. ... As the waves rush past 

 the ground opens in cracks and closes again. As the 

 cracks close the squeezed-out air blows out sand and 

 gravel, and sometimes sand and water are spurted high 

 in air. The roar becomes appalling. Through its din 

 are heard loud, deep, solemn booms that seem like the 

 voice of some higher Power speaking out of the depths 

 of the universe. Suddenly the storm subsides, the earth 

 comes speedily to rest, and all is over. 



And yet, says Major Button, this description suggests 

 but a single instance, or a few instances, of what earth- 

 quakes are like. In some the full vigour of the shock 

 comes with explosive suddenness. People find themselves 

 suddenly thrown to the earth, the ground swept from 

 under their feet. Sometimes the rolling waves of earth 

 are absent, and the movement is a rude quiver, rapidly 

 vibrating in every direction twisting, contorting, wrench- 

 ing the ground as if in a determined effort to shake it 

 into dust. Sometimes the most pronounced motion is up 

 and down, as if the earth beneath were being hammered 

 with giant strokes. Sometimes the growth, the climax, 

 the dying out of the earthquake movement are repeated 

 before the first shocks have ceased, or a few minutes after- 

 wards, or even with an interval of several hours. The 

 last-named case is, however, uncommon, though after the 

 first shocks of a great earthquake there are minor shocks 



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