274 EARTHQUAKES. 



violently, to raise itself to a great height, and then rush 

 landwards.^ 



In 1797, when Eiobamba was destroyed, the neigh- 

 bouring volcanoes were not affected, but Mount Pasto, 

 120 miles distant, suddenly ceased to throw out its 

 usual column of water. 



On the night of December 10, 1874, a strong shock 

 was felt in New England, whilst at 4.45 a.m. on 

 December 11 a shock was felt in the Pic du Midi, in 

 the Pyrenees. In the middle of December there were 

 volcanic outbursts in Iceland.^ 



It is possible that these occurrences might be the 

 results of some widespread disturbance beneath the crust 

 of the earth, or perhaps even of widely extended earth 

 pulsations. The probability, however, is that these coin- 

 cidences are accidental. When we remember that in a 

 small area like the northern half of Japan alone there 

 are periods when there are at least two shocks per day on 

 the average, it is impossible for these coincidences not to 

 exist. Less frequently coincidences between the larger 

 disturbances must occur. Over and above these accidental 

 coincidences, it would appear that in the world's history 

 periods have occurred when earthquakes were unusually 

 frequent, and at such times distant countries have suffered 

 simultaneously. This approximate coincidence in period, 

 which has been referred to when speaking of the distri- 

 bution of destructive earthquakes in historical time, does 

 not imply an exact synchronism in the single shocks. 



Small earthquakes, or, more properly speaking, local 

 tremblings, are a necessary accompaniment of almost all 

 volcanic eruptions. Tremors of this description are seldom, 

 however, felt beyond the crater, or at the most upon the 

 flanks of the mountain where the eruption is going on. 



' Phil. Trans, vol. xlii. * Am. Jour. Sci. vol. x. p. 391. 



