EARTHQUAKES AND SEAQUAKES 



75 



secondary effect of the shaking, but others, like the quebradas of 

 the southern Andes or the " earthquake cracks " in the Colorado 

 desert (Fig. 63), may have a deeper-seated origin. Many facts 

 go to show, however, that though local expansion does occur in 



FIG. 64. Diagrams to show how railway tracks are either broken or buckled 

 locally within the district visited by an earthquake. 



some localities, a surface contraction is a far more general conse- 

 quence of earth movement. In civilized countries of high indus- 

 trial development, where lines of metal of one kind or another run 

 for long distances beneath or upon the surface of the ground, such 

 general contraction of the surface may be easily proven. Com- 



FIG. 65. The Biwajima railroad bridge in Japan after the earthquake of 1891 

 (after Milne and Burton). 



paratively seldom are lines of metal pulled apart in such a way 

 as to show an expansion of the surface; whereas bucklings and 

 kinkings of the lines appear in many places to prove that the area 

 within which they are found has, as a whole, been reduced. 



Water pipes laid in the ground at a depth of some feet may be 

 bowed up into an arch which appears above the surface ; lines of 



