Earthquakes in Assam, India

State - Assam, India
Capital - Guwahati-Dispur
Population - 26,638,40 (2001)

Population per district (Top 5)
Kamrup - pop. 2,522,234
Nagaon - pop. 2,314,629
Sonitpur - pop. 1,681,513
Barpeta - pop. 1,647,201
Dhubri - pop. 1,637,344

Earthquake History
Much of Assam lies in the Bramaputra River Valley, except for a few southern districts. The northern and eastern parts of this valley are bounded by the Himalayan Frontal Thrust (HFF). In the eastern parts along with the HFF, there is the are the Lohit and Naga Thrusts. Among the large earthquakes in this region were the events in 1869 and 1897. The 1897 earthquake is well known for the dramatic accounts of violent upthrow during the shock.

Seismic Hazard

All districts of the state of Assam lie in Zone V. Since the earthquake database in India is still incomplete, especially with regards to earthquakes prior to the historical period (before 1800 A.D.), these zones offer a rough guide of the earthquake hazard in any particular region and need to be regularly updated (See also: GSHAP Hazard Map for Assam).
 

Largest Instrumented Earthquake in Assam
12 June 1897 - Near Rangjoli, Assam, M8.0
26.00N, 91.00E
This was one of the most powerful earthquake in the Indian sub-continent. The quake wreaked havoc across a wide swathe of the present states of Assam and Meghalaya. 1500 people were killed and hundreds more hurt. Damage from the earthquake extended into Kolkata where dozens of buildings were badly damaged or partially collapsed. Shaking from the event was felt across India, as far as Ahmedabad and Peshawar. Seiches were also observed in Myanmar.

Significant Earthquakes  in Assam
The following list briefly outlines known earthquakes in this region. General locations are provided for historical events for which "generalized" epicentral co-ordinates are available. Some events which were significant for other reasons are also included. This list will be updated whenever newer information is available. Please note that Magnitude and Intensity are NOT THE SAME. All events are within the state or union territory covered on this page unless stated otherwise.

Acronyms Used:
D=Depth, OT=Origin Time, Mw=Moment Magnitude, Ms=Surface Wave magnitude, Mb=Body Wave Magnitude, ML=Local Magnitude, M?=Magnitude Type unknown

10 January 1869 - Cachar (Assam), India, M 7.5
11:45 UTC, 25.00 N, 93.00 E
It caused serious damage in the region.

12 June 1897 - Near Rangjoli, Assam, M8.0
26.00N, 91.00E
This was one of the most powerful earthquake in the Indian sub-continent. The quake wreaked havoc across a wide swathe of the present states of Assam and Meghalaya. 1500 people were killed and hundreds more hurt. Damage from the earthquake extended into Kolkata where dozens of buildings were badly damaged or partially collapsed. Shaking from the event was felt across India, as far as Ahmedabad and Peshawar. Seiches were also observed in Myanmar.

21 January 1941 - Near Tezpur, Assam, Ms 6.5
02:30:16.0 UTC, 26.50 N, 92.50 E

23 October 1943 - Near Nowgong, Assam, Mw 7.2
17:23:16.0 UTC, 23.00 N, 94.00 E
Felt strongly in the region and in neighbouring Manipur. Not much is known about this earthquake as it occurred at the height of World War II when the threat of Japanese aggression on the eastern border of British India was extremely high.

15 August 1950 - Indo-China Border Region, Mw 8.6
19:39:28.5 IST/ 14:09:28.5 UTC, 28.70N 96.60E
This "Independence Day" earthquake was the 6th largest earthquake of the 20th century. Though it hit in a mountainous region along India's international border with China, 1500 people were killed and the drainage of the region was greatly affected. The resultant floods were the cause of most of the fatalities blamed on this earthquake. The initial shock was followed by thousands of aftershocks, some of which were big earthquakes in their own rights.

31 December 1984 - SSE of Silchar, Assam, Mw 6.0
23:33:37 UTC, 24.64 N, 92.89 E
20 people were killed in Cachar District and a 100 were injured. This quake was "forecast" on the basis of a seismic swarm which was followed by a period of quiescence.

9 December 2004 - Silchar region, Assam, Mw 5.4
08:49:00 UTC, 24.710 N, 92.523 E
A moderate earthquake struck the Silchar region in Assam, India, on 9 December 2004 at 14:19 PM local time causing a few injuries and minor damage to property. The earthquake had a magnitude of Mw=5.4 and was felt in many parts of north-east India and Bangladesh.