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PRELIMINARY NOTE ON THE SRIMANGAL EARTHQUAKE OF JULY 8TH, 1918

MURRAY STURAT (1919) RECORDS OF THE GEOLOGICAL SURVEY OF INDIA

VOLUME XLIX PART 3 PAGE 173-189

Selected Transcription

After a lapse of six years, since the Burma earthquake [1912 Burma earthquake] India

experienced another severe earthquake shock on the afternoon of July 8th, 1918. The shock

was felt over eastern Bengal and Assam, throughout most of Burma, and felt over north-east

India as far west as Lahore. Srimangal is situated in the tea-garden area, and whole valleys of

tea-factories and bungalows were reported to be destroyed.

The earthquake occurred at about ten minutes to four, IST, on the afternoon of July 8th.

Considering the magnitude of the shock the actual loss of life was exceedingly small, owing

to the fortunate circumstance that the earthquake occurred in the afternoon when most people

were awake and outside, while of those who were inside buildings, most were able to escape

into the open before the buildings fell.

As in most earthquakes of the destructive class, the shock near the earthquake center seems to

have come with great suddenness and without any warning. The amount of damage around

the epicentral area was considerable. Practically all the bungalows and leaf- houses on the tea

estates in the Doloi, Balisera, and Laskarpur valleys were laid flat, those only escaping that

had steel girders as a framework, and a steel girder frame for the roof. Even in these cases the

brick walls between the girders were generally shattered, and in most cases thrown down. The

Assam Bengal Railway suffered considerably. The sections Akhaura to Kalaura, Akhaura to

Asuganj, Bhairab to Tangi, Mymensingh to Bhairab, Kalaura to Shaistagang, Kalaura to

Sylhet, and Mymensingh to Netrakona were blocked and train services suspended.

Telegraphic communication with most places in south Sylhet was interrupted, and

considerable damage was done to buildings in Sylhet, Kishorganj, Brahmanbaria, Akhaura,

Agartola, Maulvi Bazar and Habiganj.

The earthquake center seems to have been in the Balisera hills, about 3½ miles south of the

railway at Srimangal, and a little to the east of Dr Mumford’s bungalow at Kalighat. At the

Kalighat tea-estate most of the bungalows, including the Post office and club buildings, fell

towards the east. At Kajurichara estate the general direction of fall was NNE. At Rajghat

estate the general direction of fall was NE. At the Puttiachara estate and Sisal Baria the

general direction of fall was north, while at Srimangal and Phulcherra estate the direction of

fall was towards the south. The directions converge approximately to a point at Kalighat, and

situated in the gap through the hills leading eastwards to the Doloi valley.

Except near the epicenter the earthquake shock seems to have been generally proceeded by a

noise, which in most cases has been linked to the noise made by a railway train crossing an

iron bridge. At the epicenter the earthquake occurred suddenly without any preliminary noise

or tremor, the sudden shock, and the noise of the falling masonry and breaking of wooden

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beams, as the bungalow collapsed, being simultaneous. At the Phulcherra tea estate, two miles

away from the epicenter, a noise, described as a grinding noise with sharp reports, was heard

as if rocks were being split and ground together; this was followed immediately by the

earthquake shock.

The reported duration of the shock varies greatly in different reports, but it seems probable

that the shock was little, if any, more than 20 seconds in duration, near the epicenter.

THE ISOSEISMAL AREA OVER WHICH THE SHOCK WAS FELT

Owing to the fact that there are exceedingly few brick or stone buildings over the area which

was seriously affected, and to the fact that such as do exist vary greatly in nature, and strength

to resist shock, it is impossible to map out isoseists according to the Rossi-Forel scale. Most

of the area where the earthquake was violent enough to damage all or nearly all brick

buildings, consists either of jungle covered hills such as the Hill Tippearh area, or of low

lying land such as that seen in south Sylhet, practically all of which was under water at the

date of the earthquake. Brick buildings are limited therefore almost entirely to Railway

buildings, and to those in isolated places such as Sylhet, Maulvi Bazar, Habiganj, Kishorganj,

Brahmanbaria, Agartala etc., and the buildings and factories of the tea estates in the valleys of

south Sylhet. Consequently I have mapped isoseists on the plan adopted by R.D. Oldham in

his investigation of the Great Indian Earthquake of 1897.

1. All places where the destruction of brick and stone buildings was practically universal.

2. Those places where damage to masonry or brick buildings was universal, often

serious, amounting in some cases to destruction.

3. Places where the earthquake was violent enough to damage all or nearly all brick

buildings.

4. Those places where the earthquake was universally felt, severe enough to disturb

furniture and loose objects, but not serious enough to cause damage, except in a few

instances to brick buildings.

5. Places where the earthquake was smart enough to be generally noticed but not severe

enough to cause any damage.

6. All those places where the earthquake was only noticed by a small proportion of

people who happened to be sensitive, and being seated or lying down were favourably

situated for observing it.

On mapping the isoseists it became evident that they are not circular or even elliptical in

shape, but are egg shaped with the narrow end pointing approximately WNW indicating that

the focus of the earthquake was not a point but a line and that the intensity of the shock was

greater at the ESE end of this line than at the WNW end. This would appear to mean that a

slip occurred along a geological fault which runs approximately WNW- ESE through the

Balisera Hills, just to the east of Kalighat, and the greatest intensity was under the

neighbourhood of Kalighat and from there the intensity diminished in a WNW direction. No

evidence of the existence of such a fault has been obtained hitherto by geological mapping,

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because practically the whole of its length or at least the length along which this slip appears

to have taken place is buried and concealed by alluvium.

The area of maximum intensity included in isoseist 1 is that of Balisera valley and part of

the Doloi valley. With few exceptions all brick buildings were found to be destroyed within

this area. Coolie lines on the tea-estates, built mostly of sun dried mud, and thatch roofs, were

leveled to the ground. The usual type of planter’s bungalow built of poorly burnt bricks, and

very thick, exceedingly heavy, thatched roofs, also collapsed in almost every case. Tea

factories and certain bungalows having steel girder frames were left standing, but the

brickwork in them was either thrown down, or left in a shattered and tottering condition, in

almost every case. There were one or two notable exceptions, particularly at the Bharaura Tea

estate, near Srimangal, where sheltered by the side of the hills the bungalow escaped with

only one or two cracks. Within the area people found it impossible to keep on their feet during

the earthquake.

The isoseist 2 embraces a much larger area, extending from a little west of Shahaji Bazar,

on the Assam Bengal Railway, to between Tilagaon and Kalaura Junction, on the same

railway. It includes practically all the Laskarpur valley, Shamshernagar with its surrounding

group of tea gardens, Maulvi Bazar and Habiganj. Practically all the railway bridges lying

within the area bounded by this isoseist were damaged by the earthquake, in many places

railway embankments settled, and practically all brick buildings were damaged—many,

having only mud instead of mortar between the bricks, were totally demolished. North of the

railway line, with the exception of Habiganj, Maulvi Bazar, and the continuation of the

Balisera Hills north of Srimangal, the rice growing country was nearly all inundated at the

time of the earthquake and consequently offered little opportunity of observing the effects of

the shock.

Isoseist 3 passes approximately through Akhaura, Agartala, Brahmanbaria, Kishorganj and

Sylhet. Most of the area embraced by it is either the jungle-clad hill country of Hill Tipperah

or the low-lying inundated plain of south Sylhet. Well built buildings in this area escaped with

practically no damage, but buildings built of brick and mud, or brick with poor quality mortar,

were either left in a tottering condition, or partly thrown down. At Sylhet many houses in the

bazaar were thrown down, and old pucca buildings that had come through the 1897

earthquake unharmed, such as the Mosque on the river front and the School, were cracked and

left tottering. The Court and the DC’s Offices however were slightly cracked. Kishorganj, at

the first sight, appears to have suffered more than one would have expected from its position

with regard to the epicenter; the SDO’s houses and those of First and Second Munsif being

utterly destroyed and the Jail being half demolished. Each of these was however a poor

quality brick-mud building whose ability to withstand the shock was small. The Munsif’s

Court at Kishorganj, which is a good brick building, escaped practically unharmed and the

railway station, another good building only cracked through subsidence of the bank on which

it is built. The brick portion of the Akhaura Railway station was practically demolished due to

the poor quality of mortar used in its construction.

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Isoseist 4 may be split into two parts, the one passing through Comilla and nearly, but not

quite, reaching to Aijal and Silchar; while the other passes just to the east of Akyab, and from

there would appear to run, in the form of an ellipse, into the Bay of Bengal in a more or less

southerly direction, passing close to but not including Kyaukpyu. The former includes

Mymensingh, Netrakona, and Cherra Poonji. A certain amount of damage to brick buildings

was done in this area but this was due to either weak construction or to the settlement of the

ground. The Deputy Commissioner, Akyab, report that the earthquake shock threw down

loose objects and ornaments and also cracked buildings. The rest of the area being under the

Bay of Bengal, nothing is known about it but the position occupied by isoseists 5 and 6 make

it appear that its shape is elliptical with its long axis running approximately north and south.

The country intervening between these two areas has been fairly well examined, and there

seems no likelihood of any connection between the two.

The next two isoseists are not yet definitely fixed, but their position can be given with fair

approximation. Isoseist 5 contains Darjeeling, Bhagalpur, Dumka, Burdwan, Monywa,

Chittagong, Kyaukpyu, Bassein and does not reach Muzaffarpur, Bankipur, Deogarh,

Calcutta, Mandalay, Prome, Henzada or Rangoon. Even within this area a certain number of

weak buildings were cracked and occasional old houses fell. Isolated cases of objects being

overturned are also reported, such as light glass flasks in a laboratory at Dacca; and the

instance of three out of a number of empty long glass phials being overturned in Calcutta.

What appears to be a case of earthquake ‘shadow’ is exhibited by the area between Kyaukpyu

and Bassein. Both Kyaukpyu and Bassein record a smart earthquake shock, felt distinctly by

everyone, where as the SDO at Ramree reports that he was unaware that any earthquake had

taken place on 8th July, and the Deputy Commissioner, Sandoway, reports only a slight shock

felt by certain people, and not every one.

The last isoseist 6 contains Lucknow, Allahabad, Bilaspur, Sambalpur, Cuttack, Bessein,

Rangoon, Myitkyina, Putao, etc. There are certain anomalies but these may be due to separate

small sympathetic shocks, and not to the main earthquake. For instance the main earthquake

was felt as far as Lucknow, but was not felt at Naini Tal or Dehra Dun. The preliminary

tremors of the earthquake began to register on the Simla Seismograph at 15h55m20s and the

large waves at 15h59m5s IST; there was also a slight local shock, easily perceptible without

instruments between two and 3 minutes to sixteen hours IST. From the Simla Seismograph,

Dr Gilbert Walker, DG of Observatories, recognizes superposed oscillation at 15h57m45s

which he thinks indicate yielding on some fault probably within two or three hundred miles of

Simla.

SURFACE EFFECTS

Cases of sand and water issuing from the ground are common in the epicentral area, and the

instance may be quoted of the Phulcherra Tea Estate where simultaneously with the collapse

of the bungalow, numerous vents occurred on the tennis court from which water and sand

spouted up to a height of several feet. When these subsided the tennis court was found to have

settled irregularly so that instead of being level it was a series of mounds and hollows. Similar

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cases of the spouting out of sand and water are reported from Sylhet, Agartala, Comilla,

Kishorganj and Netrakona. The phenomenon seems to have been exceedingly common

between Gourigram and both Netrakona and Kishorganj, the borrow pits by the side of the

railway line being frequently filled up with sand and mud that had issued through vents; some

of the wells at Netrakona filled up with sand and water and overflowed.

Cracks due to subsidence of the alluvium were not infrequent, but those were almost

invariably parallel to a road, river or embankment. In addition to the above cases occurred of

movement and bending of both tramway and railway lines. The tramway lines in both

Balisera and Doloi valleys were in places moved a distance of several feet laterally from their

alighnment; and at Gaurigram where there is a triangle instead of a turntable to enable railway

engines to turn around, the two sides of the triangle were considerably bent.

THE SRIMANGAL EARTHQUAKE OF 8 TH JULY 1918

MURRAY STUART (1926) MEMOIRS OF THE GEOLOGICAL SURVEY OF INDIA

VOLUME XLVI, PART 1, PAGE 1- 70

THE EPICENTRAL AREA

The tea estates visited by me in the Balisera valley were the Phulchara, Kalighat, Lakhaichara,

Kajurichara, Rajghat, Puttiachara and Sisal Baria. At Phulchara the Manager’s bungalow was

leveled to the ground. The Assistant’s bungalow had only one shattered room standing, and

the factory, which had a steel girder frame, was left in a tottering condition. The factory boiler

shifted, owing to the fracturing of its brickwork foundations, and two of the heavy drying

machines were loosened from their beds. Mr. Lauder, the manager of the Phulchara estate was

just outside his bungalow when the earthquake occurred. He began to run to the bungalow and

was met at the bottom of the steps by Mrs. Lauder who managed to rush out, although bricks

were falling around her as she ran. By this time the intensity of the shock was so great that

they were unable to keep on their feet, and were thrown to the ground, while the bungalow

collapsed with a crash, and on the tennis court numerous vents occurred from which water

and sand spouted up to a height of several feet. When vibration ceased the level court was

found to have settled irregularly into a series of mounds and hollows.

At Kalighat most of the bungalows were leveled to the ground. The Club was flat and all that

was to be seen was the shattered thatched roof on the ground covering the debris of the walls.

The post office had fallen bodily towards the east. The doctor’s bungalow had completely

collapsed, and it was here that the only European death occurred. Mrs. Mumford the wife of

Dr. Mumford being killed instantaneously and another lady pinned down and crushed

by the falling roof and debris. The twisted and bent steel girders testify to the intensity of

the shock. The Kalighat Manager’s bungalow was not down, but was leaning towards the east

at a dangerous angle; its brickwork being badly shattered and cracked was in danger of falling

at any moment. The Kalighat factory was perhaps less damaged than the surrounding

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factories, but the walls were badly cracked and portions of the roof had shifted towards the

east. The walls of the Church were shattered and thrown down, but the roof and iron

framework were left standing.

At Kajurichara the Manager’s bungalow was thrown flat, and from the direction of fall of

verandah pillars and also the gate posts the direction of fall seems to have been NNE. Here,

like other areas great damage had been done to leaf-houses and factory.

At Rajghat the Manager’s bungalow was down, the Assistant’s bungalow partially down and

the remainder tottering; many leaf houses were down and the factory was badly shattered and

broken. It was in the bungalow at this estate that I saw an eight-inch steel girder that had been

broken across as if it had been a fragile stick. Between the factory and the Manager’s

bungalow on this estate is a small stream which for some distance flows SW. During the

earthquake a wave is reported to have come down this stream traveling from NE to SW and to

have washed the banks considerably above the stream level.

The framework of the bungalows at Puttiachara and at Sisal Baria was in each case of steel

girders and this undoubtedly was the reason why the roofs had not collapsed though the

brickwork in the walls shattered and in many cases thrown down.

The damage on the western side of the valley was similar to that caused on the eastern, though

slightly less intense. At Satgaon Tea Estate, the four iron columns in the center of the

Manager’s bungalow held up the roof but walls shattered and most of them down; every

column on the verandah was broken. The roof of the Assistant Manager’s bungalow was a

complete wreck. Various units within the factory including hospital, office etc., was severely

damaged and many walls collapsed.

As already stated in the preliminary report the Bharaura tea estate escaped much damage; the

Jagchara estate, 2½ miles north of Bharaura although damaged but much less than expected.

Buildings were cracked but had not fallen to any extent.

The Patrakhala tea estate in the Doloi valley suffered badly. The Manager’s bungalow was

shattered and the southern end had fallen. Part of the Assistant’s bungalow was down and the

remainder leaning over dangerously. The leaf houses being built entirely of iron were intact

but the end wall of the fermenting house fell to the east.

There are three trolley systems running N-S through the epicentral area and on each the line

had bulged in places towards the east. Other than the tea estates the only place of any

importance situated within the epicentral area is Srimangal. Here many houses were thrown

down in the bazaar and the station building damaged and partially thrown down. Damage

done to the railway line within the epicentral tract does not seem to have been excessive.

Between Srimangal and Satgaon although the bridges and the lines showed evidence of

having been badly shaken, the alignment does not seem to have been very much upset. The

Udna, Billash and the Kalighat bridges show no side or end movement but in both the Udna

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and Billash bridges the abutments sank and closed in. In the pass through the Balisera hills,

between Patrakhala and Kalighat landslips of considerable size were reported.

Effects of the earthquake in some important places

Sylhet [Isoseist 3]: In Sylhet the main shock seems to have been east and west, but

considerable damage was also done in a north and south direction. Practically all the brick

buildings in the bazaar were badly cracked and very many of them fell. The musjid on the

river front near the dak bungalow was badly cracked and seven of its eight minarets fell

outwards. The high School exceedingly cracked and left standing in a tottering condition.

Both these buildings came through the earthquake of 1897 unharmed. The Circuit House,

which is a lath-and-plaster building with iron framework, of the earthquake-proof type

constructed after the 1897 earthquake, had its lath and plaster walls shattered. The outer

walls of the Jail facing east and west were both cracked through close above the ground and

bowed outwards. Just outside Sylhet, along the Peterganj road, several instances were

reported of cracks from which sand and water issued.

Dacca [Isoseist 5]: The earthquake occurred about 5 o’clock (local time). The shock lasted

nearly one minute and was felt by everybody. Several buildings were slightly cracked and a

few very old houses fell.

Calcutta [Isoseist 6]: At Calcutta the earthquake was felt by nearly every one. Only people

who were walking or moving out of doors did not feel it.

The earthquake was recorded on the Alipur seismograph at 15hrs 53min (IST) or 4.16 PM

(Calcutta time). The oscillation was so strong that the seismograph recording pens were

thrown completely off the recording drums. Vibration could be felt continued for more that 5

minutes; when vibrations were greatest buildings and trees could be seen swaying slightly and

the motion of the floor in the observatory at Alipur was distinctly visible. Some time clocks in

the observatory stopped; two of the clocks instead of beating seconds began vibrating rapidly

and indicated 2 or 3 seconds in a period which was not longer than one second, thus gained

more than 2 minutes 38.8 seconds during the earthquake.

Not a great deal of serious damage was done, but ominous cracks appeared in several new and

old buildings in and about Clive Street. In Messrs Gillanders Arbuthnot & Co’s office a crack

8 inches long occurred on the 2nd story, just above the main entrance; the N-E corner of the

Chartered Bank was cracked for about 10 feet; at the old Telegraph office, a zig-zag crack

about 15 feet in length appeared almost under the tower facing Old Court House Street; the

Currency office showed a 12 feet-forked crack over the Mission Row entrance. The Calcutta

Town Hall suffered from the earthquake; The New Municipal Market in College Street

showed a considerable crack over the entrance on Harrison Road; an old dilapidated 2 storyed

building in Telipara Lane near Shyambazar came down. In Howrah a one-storyed house next-

door to the Howrah Roman Catholic Church in Cullen Place, came down within a few

minutes of the upheaval, while a number of huts were razed to the ground.

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Time at Origin: 10h 21m 50s (GMT)

Origin (Epicenter): 24° 15′ N [24.25] 91° 42′ E [91.70]

Depth of Focus: 14 km

Foreshock: There is evidence of two or possibly three foreshocks before the main shock on

8th July. Dr. Mumford reports two from Kalighat in the Balisera valley. The first woke him up

at 2 or 3 AM on 2nd of July. The bed was vibrating and at the same time there was a loud

report at the back of the bungalow as if something had knocked against it. This shock was

also noticed at Phulcherra where a bumping and knocking noise heard. A second foreshock

was felt in the very early hours of 7th July at what Dr. Mumford estimates to have been

12.30 or 1 AM. Another or possibly the same foreshock was reported from the neighbourhood

of Badarpur. It is reported to have occurred in the early hours of the morning of 7th July, and

was noticed by a number of oil-drillers who were at Tintikri (Hilara railway station, near

Badarpur). It was also felt on the Badarpur oilfield, and was sufficiently strong to rouse slight

sleepers.

Aftershocks: A number of aftershocks are reported, some of which were strong enough to be

recorded on the seismograph at the Alipur Observatory, Calcutta. Some of the important ones

are 2 aftershocks on 8th and one on 9

th all felt at Shillong; 9 shocks felt on 11

th July, reported

from Calcutta (2) and one each from Shillong, Mymensingh, Narainganj, Srimangal, Gauhati,

Berhampur and Chandpur; 4 shocks felt on 12th July one each at Narainganj, Srimangal,

Shillong and Calcutta.

Sympathetic shock: A sympathetic subsidiary shock appears to have originated in the

neighbourhood of Madura (09° 55′ N: 77° 10′ E) within 5 minutes of the Srimangal

earthquake. This has possibly disturbed the Madras sidereal clock. The Kodaikanal and

Colombo Observatory have recorded this shock.

Re- Levelment of the line Silchar to Comilla: The line Silchar to Comilla was originally

leveled in 1911-12. Revision was undertaken in the winter of 1919-20 to investigate whether

any disturbance had taken place during the earthquake of 8th July 1918, the epicenter of which

was reported in the Records of GSI, to be in the Balisera Hills near Kalighat, 3½ miles south

of Srimangal Railway Station. It is to be regretted that the mark-stone of Charamani, H.S.

which was connected by sprit leveling in 1911-12 and the location of which cannot have been

a quarter of a mile from the epicenter, was destroyed by the earthquake and the pillar razed to

the ground. Thus no camparison of this point was possible. The knoll on which the H.S stood

and the spurs immediately south of it bore deep fissures zig-zagging down the hillsides.

The GTS bench marks north of and within a quarter of a mile of Srimangal Railway Station,

which was practically destroyed by the earthquake show no subsidence, nor is there any

evidence of regular disturbance west of Srimangal until the low range of hills six miles west

of it, and lying between Satgaon and Rasidpur is crossed. Three quarters of a mile north of

Rasidpur Railway Station, a tree bench mark at Kamaichara shows practically no alteration; a

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mile and a half west of this the settlement of all bench marks begins. The settlement varies

from one and a half inches to nine inches according to the nature of the soil and type of bench

mark, and continues uninterruptedly past Mirpur dak bungalow, Shaistaganj, and Sahaji Bazar

up to a railway bridge 30 miles from Srimangal near telegraph post No 149-15 which shows

practically no alteration in height. Thereafter settlement is occasional but very small to

Kamalasagar, beyond which no appreciable disturbance has taken place. The bench marks

that have settled include two of the embedded type, but unfortunately none on rock.

Comparing results as far as can be ascertained, no settlement took place in the epicentral area

of northeast of the epicentral axis, but in the area between the epicentral area and Isoseist 2

west south west of the former, settlement up to nine inches occurred. Those bench marks

situated on masonry above ground have generally been disturbed more than those embedded

in the soil, the latter, however show distinct settlement.

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