THE ASSAM

1,542 people were killed and hundreds injured in Assam, in this earthquake. It had a magnitude  estimated variously between Ms 8.0 and Mo 8.1. The earliest report of extreme ground acceleration is recorded for this earthquake, where stones on the roads of Shillong as said to have "vibrated like peas on a drum". Recent studies also indicate that this might have been a blind earthquake, therefore making it the largest blind earthquake ever known.

The earthquake was centred 14 kms ESE of Sangsik (Meghalaya), India, Mystery of Assam Earthquake (1897) solved April 12, 2001 The cause of the great earthquake in north east India that killed thousands and reduced buildings to rubble in a region the size of  England appears to have been settled.

Estimated to be an 8.1 magnitude quake, the extremely violent event  caused part of the overlying Shillong Plateau to shoot up nearly 15m in just three seconds. Prof. Roger Bilham (University of Colorado at Boulder)  and Oxford University Prof. Philip England believe the Assam earthquake was most likely caused by two adjacent faults rupturing beneath the Earth’s surface in India near Bangladesh.


Assam , 1950 August 15 14:09 UTC 8.6M
 

This great earthquake, destructive in Assam, has a calculated magnitude of 8.6 and Strasbourg regards it as the most important since  the introduction of seismological observing stations. Alterations of relief were brought about by many rock falls in the Mishmi Hills and  destruction of forest areas. In the Arbor Hills 70 villages were destroyed with 156 casualties due to landslides. Dykes blocked the tributaries of the Brahmaputra; that in the Dibang valley broke without causing damage,  but that at Subansiri opened after an intermal of 8 days and the wave, 7 metres high, submerged several villages and killed 532 persons.

Two thousand homes, temples and mosques destroyed. Hardest hit is the Brahmaputra Basin in NE India This shock was more damaging in Assam, in terms of property loss, than the earthquake of 1897. To the effects of shaking were added those of flood; the rivers rose high after the earthquake, bringing down sand, mud, trees, and all kinds of
debris. Pilots flyng over the meizoseismal area reported great changes in topography; this was largely due to enormous slides, some of which were photographed.

Earthquakes  in Cachar

1984 - Cachar (Assam), India, Mw 6.0
Date: 31st December 1984
Epicentre: 4.9 kilometers W of Palanghat (Assam), India
Latitude: 24.66o N (3), Longitude: 92.85o E (3), Origin Time: 23:33:35 UTC / 06:03:35 IST (3), Magnitude: Mw 6.04, Mb 5.9 (3), Moment: 1.3*10*18 Nm (3)

The earthquake was centred 4.9 kilometres W of Palanghat (Assam), India, The shock was felt in much of North-east India and Bangladesh. In the Cachar district, 20 persons were killed and 100 were injured. There was extensive damage in southern Assam. Underground pipes were  broken and the ground was cracked. Sand, mud and water spewed forth and subsidence occurred along wide stretches of the Sonai River. Two  bridges on the Sonai - Kachidharan road collapsed and others were damaged. It was felt  with an intensity of VI at Banskandi and Palanghat, Kumbhirgram, Lakhipur, Rajabazar, Silchar and Udarband.



1869 - Cachar (Assam), India, M 7.5
Date 10th January 1869
Epicentre: 9.4 kilometers N of Kumbhir (Assam), India
Latitude: 25.00o N (2), Longitude: 93.00o E (2), Origin Time: 11:45 UTC / 17:15 IST (3)
Magnitude: 7.5 (2) Max. Intensity: VIII (1)

This earthquake was centred 9.4 kilometres N of Kumbhir (Assam), India. There was heavy damage in the towns of Cherrapunji, Silchar,  Shillong and Sylhet and also in Manipur. Fissures opened on the banks of the  Surma river and sand vents threw up great amounts of sand and water. The epicentral tract was 30 - 45 kilometres long and 5 - 6 kilometres  wide lying on the northern border of the Jaintia Hills. The hypocentre had a depth of 50 kilometres.