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Sect. VII.J 



EARTHQUAKE PHENOMENA. 



215 



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onditions. 



the wave, of changes in any or a.11 of th 



Places least and most affected by the shock, and those 



fivo from any, and their local conditions, to be particularly 



noted. 



Referring now to secondary phcaoinena^ or efR^cts result- 



ing from th 



e 



(other 



sted surfaces 



measures of it), we should observe falls of rock, or land 

 slips^ to which most of the conditions of shattered building 

 apply. Land-slips change their directions frequently, i)i 

 consequence of moving over curved or tw 

 of rock : thus the previously straight furrows of a field 

 mav be found twisted after an earthquake. Scratches or 

 furrows engraven on rocky surfaces by such land-slips 



should be looked for. 



Sometimes great sea- waves are produced by the fall into 

 the sea of rock or land-slips, which need to be carefully 



r 



distinguished from the true great sea-wave produced by an 

 original impulse of the sea-bottom. Land-slips often dam 

 rivei*s, fill up lakes ; and various changes of surfiice again 

 produce basnis for new lakes, to be filled by the changed 



The circumstances, as far as possible, 

 should be accurr^-ly observed, and the chain of events 

 unwound, and all such phenomena cautiously separated 

 from actual ejections of water (temperature to be ascer- 

 tained), which are said sometimes to have happened on an 



immense scale. 



spout it up at the 



moment of shock. Wells alter their water-level, and 

 sometimes the nature of their contents. The directions of 

 the fissures and any changes in the temperature of wells 



fissures of 



nver-eourses. 



Fissures containing water often 



hould be noted. Ejections from holes or 



K- 



tt'. 





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