THE CAUSES OF EARTHQUAKES 



so to speak, forces of tremendous power which would 

 only await a favourable opportunity in order to manifest 

 themselves. The hot steam until this favourable oppor- 

 tunity arose would be absorbed by the rocks, just as hot 

 steel can be shown to absorb gases. We are thus face to 

 face with the following situation, as it is expressed by 

 Dr. T. J. J. See, the American physicist : The internal 

 temperature of the earth is extremely high with heated 

 rocks quite near the surface, while the crust is fractured 

 and leaky everywhere, and especially where the depth of 

 the sea is greatest. The sea covers three-fourths of the 

 earth's surface, and earthquakes are found to be most 

 violent where the sea is deepest, and volcanoes most 

 numerous on the adjacent shores. Can we then suppose 

 that both earthquakes and volcanoes depend on the explosive 

 power of steam which has developed in the heated rocks 

 of the earth's crust? We have said that earthquakes 

 and volcanoes are most common in regions where high 

 mountains are near deep oceans as on the westward of 

 South and Central America, the Aleutian Islands, the 

 Kurile Islands, Japan, Sumatra, Java, and other islands 

 of the East Indies bordering on the deep waters of the 

 Indian Ocean, New Zealand, and the Lesser Antilles in 

 the West Indies, Iceland, Italy, and Greece. These are 

 also the regions where, owing to the existence of high moun- 

 tains, the weight, the pressure, the tear and stress on the 

 underlying strata are greatest, and where consequently 

 there is the greater chance of strata slipping or bending or 

 giving way. Mr. John Milne divides the world into 

 eleven such great " world-earthquake " districts ; and he 



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