The Baluchistan Earthquakes of August 25th and 27th 1931 W.D.West (1934), Memoirs of the Geological Survey of India, Vol. LXVII, Part 1, Page 1-82 [Edited Transcription] In the early hours of Tuesday, the 25th August, 1931 soon after 3AM, the inhabitants of Quetta and the neighbouring district were rudely awakened by a sharp earthquake shock, which was followed some five minutes later by another shock of less intensity. This was followed by a number of tremors throughout the succeeding 66 hours, leading up to the much severe earthquake at 8:57.5 PM on Thursday the 27th. Sharigh Earthquake The epicenter of the Sharigh shocks on the 25th seems to have been near Sharigh, on the Sind-Pishin (Harnai) branch of the NW Railway. This earthquake probably just reached an intensity of 8 on the R-F scale over a small area; but the shock was evidently a shallow one, for its effects of it rapidly diminished away from the epicenter. Two persons lost their lives at Sharigh during this earthquake. It was felt over an area roughly triangular in shape, the apices being at Chaman on the west, a little east of Kila Saifulla on the east, and at Mehar in the south, the total area being approximately 31,000 sq miles. At Sharigh the bazaar built mostly of sunbaked mud, was completely ruined; while other buildings, such as the dispensary and some of the railway quarters, built of sunbaked brick and mud mortar, were severely damaged. The railway station was rather badly cracked, and chimneys overturned. Away from Sharigh the effects of the shock rapidly diminished, though Nakus and Khost were considerably damaged and a bridge between Sharigh and Nakus affected. Though clearly felt at Quetta but was not responsible for much damage there. At Ziarat however a good deal of damage in the way of cracks in buildings was caused by this shock. Down the Bolan this earthquake was felt very much less than the later earthquake of 27th. Considering the epicenter of the Sharigh earthquake located at 30° 11′ N: 67° 42.5′ E, origin time of the earthquake was calculated from seismograms of Dehradun, Colaba, Alipur and Colombo observatories utilizing arrival times of P & S waves. The time of origin calculated was 03h05m27s (IST) or 22h35m27s (GMT). Intensity 6-7 Within this area all places suffered a shock corresponding in intensity to either grade 6 or 7 on the R-F scale. At Ziarat the Sharigh earthquake reached an intensity of about 7. The two shocks that constitute this earthquake were both clearly felt here, but the first one was more severe. Several people in Ziarat stated that rumblings were heard coming from the south before each shock. Others stated that their beds shook in a N-S direction during the main shock of 25th. The damage sustained at Ziarat as a result of the Sharigh

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earthquake consisted mostly of cracks in buildings, while a few chimney pots were overturned in the police lines. The Dak bungalow suffered more damage than any other buildings. It may be noted that neither after this earthquake nor after the Mach earthquake (27th) was the earthenware pipe line at all damaged, indicating to the comparative weakness of the shocks. At Quetta the intensity of the Sharigh earthquake seems to have been a little less severe than it was at Ziarat. At Quetta a number of buildings constructed of brick with mud mortar were slightly cracked, but not came down. The town hall a poorly built 2-story building built of brick and mud mortar was slightly cracked which considerably increased by the later Mach earthquake. A 10 inch cast iron water pipe was broken in three joints. At Harnai, just east of the epicentral tract, the shock reached an intensity of about 7. Most damage was done to verandahs, purdah walls and courtyard walls, while two houses built of mud partly collapsed. At Mach and in Bolan generally the Sharigh earthquake was not severely felt; reports from most places indicate intensity of 6. At Mach bedsteads were moved and picture swung, while the walls of some of the railway quarters were slightly cracked. Other places down the Bolan were similarly affected. Just as was the case with the later Mach earthquake, the effects of this earthquake spread a considerable distance down the Kachhi alluvial plain, in accordance with the well known fact that towns situated on alluvium suffer more severely than those situated on solid rock, other things being equal. Thus the towns of Dadhar, Sanni and Bhag all experienced a shock of intensity of at least 6, thus causing the middle isoseismal line to extend a long way south to embrace these places. At Dadhar all inhabitants were awakened from sleep, but no damage was done. At Sanni and Bhag the shock was sufficiently strong to throw down loose objects and to crack a few walls. At Sibi no damage was done except a few cracks in the European Institute, a fairly high brick building with mud mortar. Intensity 1-5 In none of the places was the shock sufficiently strong to crack even the poorly constructed buildings, common in the area. Beyond the limits of the outer isoseismal line the shock was slightly felt, in particular at Rajaapur and Dehra Ismail Khan up the Indus valley. At Mastung only one shock was felt; at Kalat the shock was not felt at all. Further north, at Pishin and Kila Abdulla the shock was rather less severe than at Quetta, reaching an intensity of about 5. A few cracks in buildings observed at Pishin. At Chaman the effect was very slight being felt by some and not by others. At Hindubagh, some 11.5 miles north of Sharigh, the intensity of the shock was about 5, and was about same at Kila Saifulla. In the alluvial plain of Kachhi and the upper Sind frontier, at Lahri the shock was only strong enough to awaken some people, an intensity of about 4 indicated. At Bellpat, no damage was done, but intensity of shocks probably reached 5. Further SW the shock was of a similar intensity at Shoran, Gandava and Jhal, and even as far south as Shahdadpur the intensity was about 5. At Jacobabad the shock was just sufficient to make hanging objects swing, but not to make doors rattle or floors creak. Here and at Shikarpur the intensity was between 3 & 4 of the R-F scale. The furthest point south, at which the earthquake was felt, was Radhan, on the railway line, where the intensity was of the order of 3. The Sharigh earthquake was not felt at such places like Dadu, Johi and Sehwan.

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The Mach Earthquake After an interval of 66 hours, during which a large number of tremors occurred, the Sharigh earthquake was followed by the most severe shock of all, which took place about 8:57.5 PM on Thrusday the 27th August. The focus has now been shifted; and judging from the damage done, it was localized about the SW side of the re-entrant angle in the Baluchistan hills, namely down the Bolan pass and along the border of the Kachhi plain with hills to the west. The shock was felt over an area of not less than 370,000 sq miles and caused a large amount of damage but nothing like as great as the accounts in the newspapers indicated. It is a remarkable fact that the advent of a great natural phenomenon nearly always leads to exaggerated reports in the press. Providentially the earlier earthquake at Sharigh and the tremors which followed it had caused many of the inhabitants to sleep out of doors on the ground; the result was that the mortality was lower than it might have been if the Mach earthquake had arrived unheralded. The most spectacular effects of the earthquake were seen in the Bolan at and around the towns of Mach and Old Mach, where the majority of buildings were badly damaged; but almost equally severe damage was also sustained by some of the villages in the Kachhi plain such as Mushkaf, Naoshera, Sanni, Shoran and Gandava, where most of the mortality occurred. In all a little over a hundred lives were lost. The distribution of the isoseismal lines shown in Plate 8 corresponds to the numbers of the R-F scale and after taking everything into consideration it has been concluded that the intensity of the earthquake at the epicenter did not exceed 8 on the R-F scale. For although a very large portion of the buildings within this area were badly damaged, good brick buildings in which a lime mortar had been used, even though badly constructed from an earthquake-proof point of view, were either unaffected or only slightly cracked. The epicenter of the Mach earthquake has been placed at 29° 47.5′ N: 67° 16′ E considering the severest damage. Accordingly the origin time for the shock has been calculated from data received from the observatories; Dehra Dun, Colaba, Hyderabad [Nizamiah], Alipur and Colombo. The origin time derived is 20h57m30s (IST) or 15h27m30s (GMT). The Epicentral Tract This area, in which the greatest intensity of the earthquake was experienced, is a narrow, curved, elongated tract, and follows closely the strike of the rocks down the Bolan and the junction of the hills with the Kachhi plain. It covers an area of 1800 sq miles. Within this area the following places were most severely damaged: Old and New Mach, Kirta, Dadhar, Mushkaf, Naoshera, Sanni, Shoran, Gandava and Kotra. In each of these places the majority of the buildings were badly damaged, while they also accounted for almost all the loss of life which occurred. The Stationmaster at Mach stated that he heard a slight rumbling and had a feeling of shaking before the arrival of the main movement. At the time of the earthquake the down mail train was on the platform with about 200 passengers. During the shock the train swayed from side to side [east to west] and the driver was thrown from the engine.

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People rushed out into the open but were thrown to the ground, and for five to six minutes could scarcely stand up. Throughout the night, to the accompaniment of numerous aftershocks, rescue work was carried on in the bazaar and elsewhere, and the next morning it was found that the majority of the buildings in Mach had been badly damaged. The four inch iron pipe line, bringing water from Old Mach, had been broken at the joints and for a short while there was scarcity of water. Practically the whole of the north wall of the Central Jail, Mach [This had only been constructed some 15 months previously and had been regarded as a most up-to-date structure, built on the modern lines] has been pushed over to the south, though supported by buttresses on the north or outer side. The south wall `supported by buttresses on the south side, had not collapsed, but a long nearly horizontal crack had developed, and the upper part of the wall had moved about two inches to the south, so as to overhang the lower part. Both the east and west walls were practically undamaged. The NE-SW central radial wall overturned to the SE. In addition to the damage to the walls, the cook house and the central observation post was also damaged. Further the SE wall of the main entrance tower was cracked, and had shifted a little to SE at the top. The cells and barracks, made of burnt bricks with a proper mortar stood the shock well, only a few being cracked slightly. Some of the railway quarters cracked during the Sharigh earthquake was completely damaged during the Mach earthquake. All the buildings belonging to the civil administration, and the school and schoolmaster’s quarters, were badly damaged. The bazaar was completely demolished; the combined damage to private property belonging to the inhabitants of Mach bazaar and Kirta village was estimated to be approximately Rs. 70,000. It is remarkable that in spite of all the damage done to buildings only five lives were lost at New Mach including the two warders in the jail. At Old Mach the damage appeared to be even more complete than at New Mach, since all the buildings were constructed with a mud mortar. The railway bridge No.198 situated just above Mach was seriously affected. The bridge consisting of four spans of a total length of 460 feet is aligned NNW-SSE. The abutments of the bridge approached one another of about seven inches; the three piers in the river supporting the spans had moved towards one another. In addition there was movement of some of the spans in a lateral direction, outwards away from the centre of the bridge to the extent of about three inches in each case. The track immediately SE of the bridge had sunk about two feet. NW from Old Mach the intensity of the shock rapidly diminished. The road was badly cracked and rendered impassable at mile 40, but at Sar-i-Bolan and Hirok the intensity of the shock cannot have been more than 7. The railway stations Ab-i-Gum was considerably damaged; Panir station and surrounding buildings built of stone and mud were very badly damaged while the Peshi station was rather worse damaged. Along the main road SE of Mach intensity of shock varied within the epicentral tract. At Bibi Nani the chimneys of the levy post were all down and some walls partly collapsed. At Dranjan the shock had been rather stronger and at Gokruth a good many houses at the north end of the village collapsed. The bungalows of the Burma Oil Co, built over scree covered slope on the other side of the river were nothing but a heap of ruins. Also badly damaged was Kirta village some four miles north of Gokurth. Between miles 68.5 and 71 the road was very seriously damaged by landslips; further south at kundalani the intensity

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of shock was less, the Rest House being completely undamaged but further east at Dadhar and Mushkaf the shock was very severe. At Dadhar out of 946 houses, 576 collapsed and 316 badly cracked. Seven people were killed here, twelve injured and thirteen head of cattle destroyed. The village Mushkaf located some 3 miles NE of Dadhar have suffered worse than Dadhar; though poorly built all 300 houses in the village collapsed. One woman lost her life and three head of cattle were destroyed. The village Rindli located between the two damaged villages was practically undamaged. In Nighari and Naoshera villages most houses collapsed; no lives were however lost but three people injured and seven cattle killed at Naoshera. At Sanni the earthquake proved disastrous. Most of the houses collapsed, 42 human lives lost; four persons wounded and 52 cattle killed. It was equally terrible at Shoran; practically all houses collapsed, 46 lives were lost, 54 person wounded and about 300 cattle were destroyed. At Gandava 77 houses collapsed and 55 were cracked; no loss of human life occurred but one woman was wounded and two cattle killed. At Khari, out of 376 houses, 297 fell down and 70 were cracked. 13 lives lost and 41 cattle destroyed. Finally at Kotra, 86 out of 385 houses collapsed; three persons killed and six head of cattle perished. The Area 7 The area within isoseismal 7 covers approximately 25,700 sq miles and includes such places as Quetta, Harnai, Sanjawi, Sibi, Jacobabad and Shikarpur, the ewo latter places coming very near its outer limit. Within this area cracks appeared in walls made with mud mortar; houses of more than one story had in some cases bricks dislodged from their top storey; small moveable objects were frequently overthrown; and badly made chimneys collapsed. At Quetta, the civil station south of the Habib nala had suffered more than the Military cantonment located north of the nala. In the civil station in one or two cases cracks formed by the Sharigh earthquake were closed up by the Mach earthquake. Damage was mostly sustained by those buildings constructed of soft mud mortar; buildings constructed with lime mortar were left unaffected. The two story Town Hall built with a rather poor variety of burnt brick with mud mortar was considerably damaged. In addition to the Town Hall, two or three other buildings of three storeys had suffered damage to the top storey. As regards the civil buildings in Quetta to be repaired by Government, it was estimated towards the end of September that the cost of repairs would probably not exceed Rs. 10,000. A minor effect of the earthquake was to alter the rate of flow of water in the springs and karezes around Quetta and elsewhere. After the earthquake discharge from the Hanna river from the Zarghun mountain increased by 30%. Supply from the Chashma Tangi also increased; the karez discharges around Quetta also increased, in some cases by 50%. At Ziarat the water supply obtained by a pipe line from springs, increased by 50%, the pipe line being undamaged by the earthquake. On the other hand at the Experimental Farm in Quetta the supply of water decreased, while a tube well in the garden of the Quetta Political Agents house had nearly dried up, though there had previously been a free flow. Supply had also decreased about 50% at Kolpur that gets water through pipe line from Dozan.

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At Ziarat the occupants above the main road seem to have felt the Sharigh earthquake worse than the Mach earthquake, while in the lines and bazaar below the road the Mach earthquake was regarded as having been the more severe. At places like Harnai, Nakus, Sharigh and Khost the effect of Mach earthquake was merely to emphasise the damage already done by the Sharigh earthquake. At Sharigh the railway menials’ quarters, badly cracked by the Sharigh earthquake, collapsed during the Mach earthquake. At Sibi the Mach earthquake was felt much more severely than the Sharigh earthquake. One (NE corner) of the four minarets at the corner of a mosque fell towards E30N.Walls of the hospital building were slightly cracked. The European Institute was badly cracked at the south end; the most severely damaged building was the Drivers’ house; it is a high building, and had been slightly cracked on the 25th; on 27th the wall and roof on the N35W side collapsed. At Lahri, some 30 miles SE of Sibi one shop in the bazaar collapsed and some walls fell down, while a good many others were cracked. One woman was killed and two cattle perished. At Jacobabad the ground seemed to undulate for aboput a minute; the plates and cutlery on the dining table shot backwards and forwards and hanging lamps swung violently. Little damage was done at this place, though at Shikarpur, not far away one wall collapsed. At Pandran, about 30 miles SE of Kalat, large falls of rock occurred; several houses collapsed, while one person died and two others injured. Further two flocks of sheep and goats numbering about 200 were destroyed along with two sheperds at Gazag, near Narmakh, owing to the collapse of the mountain side. The Area 6 The area enclosed within isoseismal 6 is a relatively narrow one, measuring about 16,000 sq miles. It includes places as Pishin, Mastung, Kalat, Bela, Dadu, Larkana and Kila Saifulla. Within the area the walls of buildings were only rarely cracked, loose objects were overthrown, while pendulum clocks were stopped at many places. The Area 4-5 This area covers approximately 90,000 sq miles and includes places as Chaman, Kila Abdulla, Hindubagh, Dera Ismail Khan, Multan, Sukkur, Karachi and Nushki. Within the areathe shock was distinctly felt by persons in motion; doors and windows rattled and wooden floors creaked; furniture were disturbed; no material damage was done. On an average the shock lasted from 10 to 15 seconds. The Area 1-3 The area includes places in which the shock could only be felt by persons sitting or lying down, and not by those in motion. The boundary between this area and the rest of India in which the shock was not felt, is necessarily rather vague. A few places within this area where the shock felt include; Hyderabad, Jaisalmer, Jodhpur, Kishengarh, Bikaner, Ajmer, Lahore etc.

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Aftershocks The Sharigh and Mach earthquake were followed for some weeks by a latge number of aftershocks of varying intensity, which gradually decreased in both number and severity, though as late as December the 19th quite an appreciable shock was felt. After September 1st aftershocks became less frequent, though one or two occurred which were strongly felt at Quetta, of which that was felt at 2-40 AM on the 8rh September was generally thought to have been the most severe of all the aftershocks. Sympathetic Shock Two reports were received from Gulmarg, in Kashmir, indicating that an earthquake was felt there at about the same time of the Mach earthquake. As this place is well outside the area within which the Mach earthquake was normally felt, and was separated from this area by a large expanse of country in which the earthquake was definitely not felt at all, it seems as though the shock must have originated locally. The two reports gave the time of the shock as 20-56 and 20-58 on August 27th, and stated to last for 2-3 seconds. The shock appears to have had an intensity of about 4 on the R-F scale. It seems extremely unlikely that a shock of this intensity was directly due to the Mach earthquake and may be called a sympathetic shock.

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