EARTHQUAKES IN GEOLOGY 



begin to fly about ; those that are lightly hung break 

 from their fastenings. The shaking increases in vio- 

 lence. The floor begins to heave and rock like a boat 

 on the waves. Plaster ceilings fall, the walls crack, the 

 chimneys go crashing down, everything moves, heaves, 

 tosses. Huge waves seem to rush under the founda- 

 tions as if driven by a gale. The swing now becomes 

 longer and still more powerful. The walls crack open. 

 A sudden lurch throws out the front wall into the street, 

 or tears off or shakes down in rubble the whole corner 

 of the building. Then comes a longer swaying motion, 

 not unlike a ship at sea, but more rapid ; not alone from 

 side to side, but forward and backward as well, and both 

 motions combined with a wriggle which it seems impos- 

 sible for anything to withstand. It is this compound, 

 figure-8 motion which is so destructive, rending asunder 

 the strongest structures as if they were built of clay. It 

 is the culmination of the quake. It settles into a more 

 regular and less violent swing ; then suddenly abates and 

 ceases. 



Out in the open country the signs and portents are of 

 a different character. The first intimation is a strange 

 sound. Some have likened it to the sighing of pine 

 trees in the wind, or to falling rain ; others to the distant 

 roar of the surf; others to the far-off rumble of the 

 railway train. It grows louder. The earth begins to 

 quiver, then to shake rudely. Soon the ground begins to 

 heave. Then it is actually seen to be traversed by visible 

 waves something like waves at sea, but of less height 

 and moving much more swiftly. The sound becomes a 



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