Earthquakes in West Bengal, India

State - West Bengal, India
Capital - Kolkata (Calcutta)
Population - 80,221,171 (2001)

Population per district (Largest)
East - pop. 244,790

Earthquake History
Earthquakes have originated in many places in West Bengal. Most of the earthquakes occur in the Himalayan ranges in the northern part of the state or are deep earthquakes within the Bengal fan. The most damaging earthquake so far has been the 1897 earthquake which caused widespread damage in the city of Kolkata. Several faults have been identified in this region out of which many show evidence of movement (4) during the Holocene epoch. The Main Boundary Thrust run along the southern flanks of the Sikkim Himalayas. In addition to that there are several active faults in the vicinity of Shiliguri. The Garhmayna-Khanda-Ghosh fault which connects to the Rajmahal Fault in the north, runs in a north-south direction in the western part of the state and terminates near Sahibganj in the north. However, it must be stated that proximity to faults does not necessarily translate into a higher hazard as compared to areas located further away, as damage from earthquakes depends on numerous factors such as subsurface geology as well as adherence to the building codes.

Seismic Hazard

The seismic hazard map of India was updated in 2000 (6) by the Bureau of Indian Standards (BIS). There are no major changes in the zones in West Bengal with the exception of the merging of Zones I and II in the 1984 BIS map. Western sections of the northern districts of Jalpaiguri and Kooch Bihar lie in Zone V. The remaining parts of these two districts, along with the districts of Darjeeling, Uttar Dinajpur, Dakshin Dinajpur, Maldah, 24 North Parganas and 24 South Parganas lie in Zone IV. The rest of the state along with the city of Kolkata, lies in Zone III. 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 West Bengal).

Largest Instrumented Earthquake in West Bengal
15 April 1964 - Sagar Island, West Bengal, Mb 5.2 (4).
21.600 N, 88.700 E, D=036.0 kms, OT=08:35:27 UTC (4)
Felt in southern West Bengal and eastern Orissa including at Kolkata and Hugli. Damage in areas near the epicentre such as at Contai and Diamond Harbour. The maximum intensity in Kolkata was V.

Significant Earthquakes in West Bengal
The following list briefly outlines known earthquakes in this region which either had observed intensities of VI or higher (historical events) or had known magnitudes of 5.0 or more (instrumented events) in southern West Bengal. Earthquakes in the Sikkim Himalayas in the state with intensities of VII or higher (historical events) or with known magnitudes of 5.5 or more are listed. General locations are provided for historical events for which "generalized" epicentral co-ordinates are available. 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

04 June 1764 - Kandi-Khargram area, West Bengal.
24.000 N, 88.000 E (1)
Maximum observed intensity VIII (1).

01 February 1811 - Kolkata area, West Bengal.
22.600 N, 88.400 E (1)
Maximum observed intensity VI (1).

03 April 1822 - Kolkata area, West Bengal.
22.600 N, 88.400 E (1)
Maximum observed intensity VII (1).

08 July 1828 - Kolkata area, West Bengal.
22.600 N, 88.400 E (1)
Maximum observed intensity VII (1).

08 July 1834 - Rangpur area, Bangladesh.
25.800 N, 89.400 E (1)
Maximum observed intensity VIII (1).

21 July 1834 - Rangpur area, Bangladesh.
25.800 N, 89.400 E (1)
Maximum observed intensity VIII (1).

11 November 1842 - Bihar-Bengal.
27.000 N, 88.300 E (1)
Maximum observed intensity IX (1). Damage (12) at Munger, Bihar. Felt (1) at Kolkata, Darjeeling and Guwahati. Seiches (10) observed in the northern Bay of Bengal.

10 August 1843 - Darjeeling area, West Bengal.
27.000 N, 88.300 E (1)
Maximum observed intensity VII (1).

06 August 1845 - Kolkata area, West Bengal.
22.700 N, 88.400 E (1)
Maximum observed intensity VII (1).

27 February 1849 - Darjeeling area, West Bengal.
27.000 N, 88.300 E (1)
Maximum observed intensity VIII (1).

09 February 1851 - Kolkata area, West Bengal.
22.600 N, 88.400 E (1)
Maximum observed intensity VII (1).

May 1852 - Darjeeling area, West Bengal.
27.000 N, 88.300 E (1)
Maximum observed intensity IX (1).

16 February 1861 - Kolkata area, West Bengal.
22.600 N, 88.400 E (1)
Maximum observed intensity VIII (1).

29 March 1863 - Darjeeling area, West Bengal.
27.000 N, 88.300 E (1)
Maximum observed intensity VII (1).

20 December 1865 - Rajshahi-Murshidabad area, India-Bangladesh border.
24.400 N, 88.700 E (1)
Maximum observed intensity VI (1).

25 December 1865 - Krishnanagar area, West Bengal.
23.400 N, 88.500 E (1)
Maximum observed intensity VI (1).

09 August 1869 - Darjeeling area, West Bengal.
27.000 N, 88.300 E (1)
Maximum observed intensity VII (1).

12 June 1897 - Assam-Meghalaya, Mw 8.1 (12).
26.000 N, 91.000 E
This is the most powerful intraplate earthquakes in the Indian sub-continent. Close to 1,500 people were killed in Assam, Meghalaya and adjoining parts of the Bengal. Damage (MM VII) in the Kolkata are and to a much greater extent in the duars of northern West Bengal.

29 September 1906 - Kolkata area, West Bengal.
22.600 N, 88.400 E (1)
Maximum observed intensity VI (1).

06 December 1906 - Kolkata area, West Bengal.
22.600 N, 88.400 E (1)
Maximum observed intensity VI (1).

02 July 1930 - Dhubri, Assam, Ms 7.1 (4).
25.800 N, 90.200 E, OT=21:03:34 UTC (4)
Most masonry buildings in Dhubri were destroyed. Felt in much of the Bengal and Assam.

15 January 1934 - Indo-Nepal Border region, Mw 8.0 (13)
26.500 N, 86.500 E, OT=08:43:25 UTC (4)
Close to 10,700 people killed in North Bihar and Nepal. Heavy damage in the towns of Muzaffarpur, Motihari, Dharbhanga, and Munger (Monghyr). Tremors were felt (11) all over the Indian subcontinent, and were felt strongly at many places in West Bengal including Kolkata.

21 March 1935 - Pabna, Bangladesh, Ms 6.2 (4).
24.250 N, 89.500 E, D=080.0 kms, OT=00:04:02 UTC (4)
Prolonged tremors were felt in much of the Bengal including at Kolkata. An aftershock occurred on 23 April 1935 and was also widely felt in the region.

10 December 1949 - Kishoreganj area, Bangladesh, M? 6.0 (8).
26.000 N, 89.000 E, OT=19:37:14 UTC (8)
This earthquake was located to the north-east of Saidpur and to the north-west of Rangpur in northern Bangladesh along the border with India.

15 August 1950 - Arunachal Pradesh, Mw 8.6 (GSI).
24.250 N, 89.500 E, D=080.0 kms, OT=00:04:02 UTC (GSI)
This is the most powerful earthquake in South Asia. The earthquake caused damage to buildings as far as Kolkata.

21 August 1960 - Samthar-Kalimpong area, West Bengal, Ms 5.5 (4).
27.000 N, 88.500 E, D=029.0 kms, OT=03:29:04 UTC (4)
This earthquake was located in the Darjeeling-Kalimpong area of northern West Bengal.

15 April 1964 - Sagar Island, West Bengal, Mb 5.2 (4).
21.600 N, 88.700 E, D=036.0 kms, OT=08:35:27 UTC (4)
Felt in southern West Bengal and eastern Orissa including at Kolkata and Hugli. Damage in areas near the epicentre such as at Contai and Diamond Harbour. The maximum intensity in Kolkata was V.

23 June 1976 - South of the Sunderbans, West Bengal, Mb 5.0 (4).
21.180 N, 88.620 E, D=050.0 kms, OT=15:38:42 UTC (4)
This earthquake was located in the Bay of Bengal off the Ganga Delta.

19 November 1980 - Gangtok area, Sikkim, Ms 6.1 (4).
27.400 N, 88.800 E, D=047.0 kms, OT=19:00:45 UTC (4)
8 people injured and damage in Gangtok. Felt throughout eastern India, Bangladesh, Bhutan and Nepal (7).

26 March 1981 - Chingrakhali-Bhairabnagar area, West Bengal, Mb 4.9 (4).
21.180 N, 88.620 E, OT=02:47:10 UTC (4)
This earthquake was located along the India-Bangladesh border to the east of Canning, West Bengal.

12 June 1989 - Sunderbans, Bangladesh, Mw 5.7 (7).
21.861 N, 89.763 E, D=006.0 kms, OT=00:04:09 UTC (7)
1 person was killed and 100 injured in the Banaripara area of Bangladesh. Felt in much of eastern Bangladesh including at Chittagong and Rangpur. It was also felt in Meghalaya, India.

20 June 2002 - Jayachari-Rajshahi, Bangladesh, Mw 5.1
25.868 N, 88.874 E, D=037.8 kms, OT=05:40:43 UTC
A moderate earthquake struck northern Bangladesh, on 25 June 2002 at 11:40 AM local time, causing several injuries in the Rajshahi division, Bangladesh. It had a magnitude of Mw=5.1 and was felt for close to 45-seconds.

28 November 2005 - Ganga Canyon, South of the Sunderbans, Mb 4.7
21.015 N, 89.158 E, D=010.0 kms, OT=16:57:13 UTC
A light earthquake occurred in the Ganga Canyon in the northern Bay of Bengal, off the Sunderbans on 28 November 2005 at 22:27 PM local time in India. The earthquake had a magnitude of Mb=4.7 and was felt in southern parts of West Bengal.

References
01) Chandra, U., "Earthquakes of Peninsular India--A seismotectonic study", Bulletin of the Seismological Society of America, Vol. 67, No. 5, pp. 1387 - 1413, 1977.

02) Dasgupta, S., Pande, P., Ganguly, D., Iqbal, Z, Sanyal, K, Venkatraman, N.V., Dasgupta, S., Sural, B., Harendranath, L., Mazumdar, K., Sanyal, S., Roy, K., Das, L.K., Misra, P.S., Gupta, H.,  "Seismotectonic Atlas of India and its Environs", Geological Survey of India, 2000.

03) Giardini, D., Grünthal, G., Shedlock, K.M., Zhang, P., "The GSHAP Global Seismic Hazard Map", Annali di Geofisica, Vol. 42, No.6, p. 1225 - 1230, 1999.

04) India Meteorological Department, Lodhi Road, New Delhi.

05) International Seismological Centre, On-line Bulletin, http://www.isc.ac.uk/Bull, Internatl. Seis. Cent., Thatcham, United Kingdom, 2001.

06) IS 1893 (Part 1): 2002 Indian Standard Criteria for Earthquake Resistant Design of Structures Part 1 General Provisions and Buildings (Fifth Revision).

07) U.S. Geological Survey, National Earthquake Information Center, Golden, CO, USA.

08) Tandon, A.N., and Srivastava, H.N., "Earthquake occurrence in India: Earthquake Engineering (Jai Krishna Vol.)", pp. 1 - 48, Sarita Prakashan, Meerut, 1974.

09) Bilham, R. and P. England, "Plateau pop-up during the 1897 Assam earthquake.", Nature, 2001.

10) Berninghausen, W. H., "Tsunamis and Seismic Seiches reported from regions adjacent to the Indian Ocean", Bulletin of the Seismological Society of America, Vol. 56, No.1, p 69 - 74, 1966.

11) Memoirs of the Geological Survey of India, Vol.73, pp. 100-101, Kolkata, 1939 (1981 Reprint).

12) Bilham, R. and P. England, "Plateau pop-up during the 1897 Assam earthquake.", Nature, 2001.

13) Pacheco, Javier F., and Sykes, Lynn R., "Seismic moment catalog of large shallow earthquakes, 1900 to 1989" Bulletin of the Seismological Society of America, v. 82, no. 3, p. 1306 - 1349, 1992.

14) Wessel, P., and Smith, W.H.F., "Free software helps map and display data", EOS Trans., AGU, 1991, 72, 441, 445.