288 



KNOWLKIJGI-: 



August, 1912. 



residents of native states. Of still greater service 

 was the personal inspection of the central district 

 made by Mr. Middlemiss and three other officers 

 of the Geological Survey. They collected many 

 details fnnn survivors, and examined the more 

 durable effects of the shock on the ruined towns 

 and \illages. 



The loss of life, as already noticed, was in great 

 jiart due to tiic early hour at which the eartluiuake 

 occurred. But there was another contributing cause 

 — the sudden onset of the shock. It was at first 

 supposed that no sounds or tremors heralded the 

 coming disaster. Further inquiry showed that dur- 

 ing the previous thirt\- hours, a few weak shocks 

 were observed. There was nothing, however, to 

 distinguish them from others which might occur 

 alone. They attracted little, if any, notice, and in 

 all jiroliability they would have passed unrecorded 

 had it not been for their disastrous successor. Prac- 

 tically, this broke without warning on the central 

 area. The initial tremors must iiave been brief, for 

 the death-rate at Kangra and Dharmsala was un- 

 usually high. From single-storeyed barracks and 

 bazaars, the able-bodied had time to save themselves. 

 From loftier dwellings, at least ten seconds, as Mr. 

 Middlemiss estimates, would be required for escape. 

 Yet even this brief interval was not vouchsafed their 

 inhabitants. They had time to move, but not to 

 escajjc, before the shock attained its full strength. 

 In the Gburka barracks at Dharmsala. in which one 

 hundred and thirty-five men were killed, there were 

 hardly any who had not left their beds. 



The area disturbed by the earthquake is shown in 

 the sketch map given in Figure 325. The curves 

 are isoseismal lines — lines of equal strength of shock. 

 It was found possible to draw six of these lines, the 

 intensity of the shock being estimated by means of 

 an arbitrary standard known as the Rossi-Forel 

 scale. Near the central area the data are numerous, 

 owing to the personal survey made by Mr. Middlemiss 

 and his colleagues, and the map contains isoseismal 

 lines corresponding to each of the three highest 

 degrees of the intensity-scale. Outside the isoseismal 

 line of intensity 8, the records were more scant\-. 

 They were furnished by persons who answered the 

 inquiries in newspapers or filled in the earthquake- 

 forms, and they depend on the personal impressions 

 of observers, not on the more or less permanent 

 effects of the shock. In drawing the isoseismal lines, 

 it was found necessary to group together records of 

 intensities 7 and 6, 5 and 4, and 3 and 2. All three 

 outer lines are, however, incomplete. The\- traverse 

 territory from which no observations were forth- 

 coming. The outermost line of all includes the 

 whole area within which the shock was sensible to 

 persons at rest. If we imagine it completed in the 

 course which its last observed trends seem to 

 indicate, it includes an elliptical area about one 

 thousand six hundred and fifty miles long, extending 

 from yuetta on the west to beyond Calcutta on the 

 east, and about one thousand live hundred miles 

 from north to south. The total disturbed area, 



including the portion frf)m which records are 

 unobtainable, therefore falls but little short of two 

 million .s(|uare miles. 



Of greater interest are the three inner isoseismal 

 lines, the course of which it was possible to delineate 

 w ith some approach to accuracy. These are show n 

 on a larger scale in Figure 326. The innermost 

 isoseismal of the three, includes an area of about 

 two hundred square miles. Within it are such 

 places as Kangra and Dharmsala, in which the 

 destruction to life and propert)' was sweeping. Only 

 the strongest buildings, such as the Dharmsala 

 magazine and treasury, were able to withstand the 

 shock ; ordinary houses were not only destroyed, 

 they were reduced to flattened heaps of debris. The 

 next isoseismal (No. 9) encloses the area of moderate 

 destruction. Towns and villages were ruined, but 

 not totally. A few well-built bungalows could after- 

 wards be used in i^art as shelters, a room or verandah 

 being here and there left standing. Others could be 

 repaired by the renewal of portions of the walls and 

 roofs. The difference between the two zones was 

 very marked : in the former one w andered over the 

 prostrate ruins of houses, in the latter between 

 fragments of partly-standing walls. 



Still less disastrous were the effects of the shock 

 within the next isoseismal, that of intensity 8. 

 Approaching it from the outside, sensible damage to 

 buildings began to be plainly visible ; but the 

 damage was generally slight. It amounted to little 

 more that a fallen roof or wall or a bulging tower, 

 damage that was so easil\- repaired that the inhabit- 

 ants soon returned to their houses. The most 

 remarkable feature of the isoseismal is its division 

 into two detached portions, between which the 

 intensit}- of the shock was manifestly less. The 

 larger portion surrounds the isoseismals 9 and 10 

 the smaller includes Dehra Dun, Mussoorie and 

 other places. The centres of the two curves are 

 about one hundred and twenty miles apart in a 

 north-west and south-east line, while the longer axes 

 of the curves are roughly parallel. 



The rate of decline in intensity in various direc- 

 tions from the central area is clearh' shown by the 

 form and relative positions of the isoseismal lines. 

 These curves also bound areas within which the 

 nature of the shock distinctly varied. From w ithin 

 the central isoseismal, it was found difficult to collect 

 any personal observations. Nearly half of the in- 

 habitants were crushed beneath fallen buildings, the 

 majoritv of the survivors were unnerved by terror. 

 The few records available show, however, that the 

 shock was very different from that usuall\- experienced 

 during earthquakes. At Dharmsala there were a 

 few gentle tremors, followed by two or three severe 

 shocks, the second of which was the most 

 disastrous. So far as can be judged from the per- 

 sonal evidence, the shocks consisted of "a mass 

 movement in a horizontal direction and back again 

 — not so much a fierce shaking as a drag of the 

 ground in one direction and then in another like the 

 wash and back-wash of a wave on shore." In the 



