AUGL'ST, iqi2. 



K\0\VLi:i)GE. 



289 



words of one observer, "the houses lurched forward 

 w ith violence and came down as if made of cards." 



In the next zone, that between tht- isoseismals 10 

 and 9, the nature of the earthquake changed to a 

 single forward thrust. There appear to have been 

 no preliminary tremors, but simplyone great vibration, 

 which increased in violence to a maximum and then 

 died down. The earth is said to have moved in 

 waves, while trees swayed to within a few feet of 

 the ground, and it was difficult for anvone to stand 

 upright. The duration of the shock, as taken h\ a 

 stopwatch, was one and a ijuarter minutes. 



In the detached 

 portion of the iso- 

 seismal 8, \\hich in- 

 cludes Dehra Uun and 

 Mussoorie, the shocks 

 were of the usual 

 vibratory character. 

 They began with 

 tremors or quiverings 

 lasting for several 

 seconds, like those 

 caused by a dog 

 scratching itself under 

 the bed. Then came 

 a pause of a few 

 seconds, followed b\' 

 two or three violent 

 oscillations or groups 

 of stronger vibrations, 

 the whole lasting for 

 one or two minutes. 

 That the shock was 

 still strong is evident Figure 326. I 



from such descriptions 



as " an irregular motion, the observer being jerked 

 from side to side, and then all round " or " as if 

 taken by the shoulders and shaken violently." 

 Persons were unable to stand or walk properly, 

 trees swayed and tents rocked as if in a gale. 

 Then the shocks died away gradually as the}- had 

 begun. 



With still increasing distance, the fierceness of the 

 shocks declined. Rapid \il)rations, of three or four 

 a second, were manifest within the next two zones, 

 but the great oscillations of the central area were 

 smoothed down into a slow rolling or undulating 

 motion, such as is felt on board a steamer in a 

 moderate sea or in an open boat at sea. By the time 

 the earthquake reached the outermost zone of all, 

 that in which the shock w-as just sensible, the quick 

 vibrations were all quenched, there was merely a 

 gentle rocking of beds, water in tanks swayed, and 

 in very distant places the bubbles in the tubes of 

 levels were seen to oscillate. 



In one respect, the Kangra earthquake differed 

 from others of equal or greater violence — there is no 

 visible evidence whatever of deep-seated changes in 

 the earth's crust. In such earthquakes as those of 

 Mino-Owari (Japan) in 1891 or Assam in 1897 or 

 California in 1906, the fractures or faults along 



which the originating movement took place were 

 continued up to the surface. .Along these fractures 

 there were displacements, both vertical and horizon- 

 tal. Rivers were ponded back so as to form lakes, 

 roads and boundar\--fence3 were severed and their 

 shifted ends were left standing several yards apart. 

 In places, the crust was so compressed that allot- 

 ments were reduced in width. The form of the 

 surface was changed so that distant objects, formerly 

 hidden by intervening mountain-spurs, iiecame 

 visible. In the Kangra and Dehra Dun districts, 

 there were none of these changes. " Not a single 



railway has recorded 



any damage to the 

 track, not a single 

 road or path has been 

 deflected, raised or 

 lowered, no rivers or 

 streams have changed 

 their courses or been 

 temporarily dammed 

 up — except as due 

 directly to landslips." 

 Surface fissures of 

 course there were in 

 abundance in loose 

 friable ground, but in 

 no case did they differ 

 from those which 

 might be produced by 

 a violent shaking. The 

 distribution of damage 

 within the central 

 areas is also uniform ; 

 soseisiiial Lines. there is no tendency 



to grouping along 

 lines of exceptional destruction. 



All this seems to indicate that the focus of the 

 earth(|uake was unusually deep-seated. How great 

 the depth was we have no sure means of ascertain- 

 ing. Mr. Middlemiss has endeavoured to form an 

 estimate b\- employing a method which Major 

 Dutton devised in his investigation of the Charleston 

 earthquake of 1886. .According to this method, the 

 depth of the focus is about one anil three-quarter 

 times the distance of the region in which the 

 intensity of the shock varies most rapidly from that 

 which lies vertically above the focus. The method, 

 if correct in principle, would be difficult to apply. 

 The intensity of the shock is subject to so many 

 abrupt variations that it is hardly possible to locate 

 the band in which the rate of change is greatest. 

 Moreover, the method takes no account of the loss 

 of energy, as the waves traverse the su|)erficial layers 

 of the crust. We cannot, therefore, feel much 

 contidence in Mr. Middlemiss' estimate that, in the 

 neighbourhood of Kangra and Dharmsala, the depth 

 of the focus must be between twelve and twenty-one 

 miles, while, about fifty miles farther to the east- 

 south-east, it must be between about twenty-one 

 and forty miles. All that we can feel sure of is that 

 the depth of the focus was considerable, and that 



