NATURE OF FOCUS, DEPTH, ETC. 331 



the time evidence which might have yielded data in this connection 

 is too unreliable in the more central region to afford any basis for 

 argument whilst outside that area it is distinctly at variance with the 



theory. 



It is therefore probable that the origin of the Kangra earthquake 

 ^ , was at some considerable depth, and of compara- 



Depth of origin < m *■ 



probably consider- tively simple shape, a conclusion reached also by 

 able, and shape other reasonings from the area of most rapidly 



diminishing surface intensity as illustrated by the 

 isoseists. 1 This line of argument was given in my preliminary report 



in the " Records, " and, after carefully considering 



Further considera- . ....*' 



tions based on dis- ** agwn, I am stl U of opinion that it represents as 

 position of the iso- nearly as possible the actual state of affairs and 

 requires no modification owing to more complete 

 knowledge. It therefore may be repeated here. 



We may note the following already established peculiarities about 

 the isoseismal lines : — 



(1) The elongated epicentral tract enclosed within the last 3 iso- 



seismals of highest intensity in the Kangra- Kulu area. 



(2) The close approximation of their curves at the west-north- 



west end of that tract. 



(3) Their widely-separated positions in an opposite direction, viz., 



east-south-east. 



(4) The small, isolated ellipse forming the southern part of iso- 



seismal No. 8 in its course round the Mussoorie area. 



With regard to (1) the elongated form of the Kangra-Kulu epicen- 

 tral tract, it seems certainly to indicate that the original earthquake 

 impulse proceeded from a centrum of thi nature of a line or plane 

 following beneath this longitudinally extended tract. 



1 The earthquake shadows and other minor irregularities Manifestly due to 

 the hills do not affect this conclusion. 



