Earthquakes in Tamil Nadu & Puducherry, India

State - Tamil Nadu, India
Capital - Chennai (Madras)
Population - 62,110,839 (2001)

Union Territory - Puducherry
Capital - Puducherry
Population - 973,829 (2001)

Million+ Cities
Chennai - pop. 4,216,268

Population per district (Top 5)
Chennai - pop. 4,343,654
Coimbatore - pop. 4,271,856
Vellore - pop. 3,477,317
Salem - pop. 3,016,346
Villupuram - pop. 2,960,373

Earthquake History
Though not as seismically active as states in the northern and western parts of the country, small to moderate earthquakes have occurred in the state of Tamil Nadu. The frequency of earthquakes is low i.e. the gap between moderate sized events is fairly long. Seismic activity in the recent past has occurred in clusters (2) along the borders with Andhra Pradesh, Karnataka and Kerala. Several faults have been identified in this region out of which many show evidence of movement (2) during the Holocene period. The east-west trending Cauvery Fault, Tirukkavilur-Puducherry Fault and Vaigai River Fault and the north-south trending Comorin-Point Calimere Fault and Rajapatnam-Devipatnam Fault are some of them and run close to major urban centres like Coimbatore, Madurai, Nagapattinam, Thanjavur and Puducherry. 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). According to the new map more areas of Tamil Nadu are susceptible to damage from earthquakes than previously thought. The city of Chennai, formerly in Zone II now lies in Zone III. Districts in the western part of the state, that lie along the border with Kerala also lie in Zone III, along with districts along the border of Andhra Pradesh and a section of the border with Karnataka. The maximum intensity expected in these areas would be around MSK VII. The rest of the state lies in Zone II. 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 Tamil Nadu & Puducherry).

Largest Instrumented Earthquake in Tamil Nadu & Puducherry
26 September 2001 - Off the coast of Puducherry, Mw 5.5
11.984 N, 80.225 E, D=010.0 kms, OT=14:56:55 UTC
A moderate earthquake occurred in the Bay of Bengal, off the coast of the union territory of Puducherry, on 25 September 2001 at 20:26 PM local time resulting in three deaths and minor damage to property in Puducherry and coastal Tamil Nadu.  It had a magnitude of Mw=5.5.

Significant Earthquakes in Tamil Nadu & Puducherry
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 M5.0 or more (instrumented events). 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

28 January 1679 - Bay of Bengal.
Felt at Fort George (16) in Chennai. This quake was also felt (16) in southern Myanmar and in the Bengal. This event could have been a large magnitude event in the Andaman & Nicobar Islands, judging from a comparison of the felt area of the 1881 and 1941 earthquakes.

09 December 1807 - Poonamalee-Avadi area, Tamil Nadu.
13.100 N, 80.100 E (3)
Maximum observed intensity VI (3). This event might be the same as one listed for December 10, 1807 and the confusion might have arisen from the interpretation of the record mentioning the event.

10 December 1807 - Chennai area, Tamil Nadu.
13.100 N, 80.300 E (2)
Maximum observed intensity VI (2). This event might be the same as one listed for December 09, 1807 and the confusion might have arisen from the interpretation of the record mentioning the event

16 September 1816 - Chennai area, Tamil Nadu.
13.100 N, 80.300 E (10)
Maximum observed intensity VI (10). Also see 11, 12.

29 January 1822 - Vandavasi (Wandiwash) area, Tamil Nadu.
12.500 N, 79.700 E (2)
Maximum observed intensity VI (2).

02 March 1823 - Sriperumbudur-Chettipattu area, Tamil Nadu.
13.000 N, 80.000 E (1)
Maximum observed intensity VI (1).

03 January 1859 - Kadaladi-Polur area, Tamil Nadu.
12.500 N, 79.000 E (10)
Maximum observed intensity VI (10). Also see 11, 12.

03 July 1867 - Villupuram-Valavanur area, Tamil Nadu.
12.000 N, 79.600 E (2)
Maximum observed intensity VII (2). This area is located to the west of the union territory of Puducherry.

28 February 1882 -  Udagamandalam (Ooty/Ootacamund) area, Tamil Nadu.
11.460 N, 76.700 E (2)
Maximum observed intensity VII (2). Felt at Calicut in Kerala (10,14).

12 August 1889  - Chennai area, Tamil Nadu.
13.100 N, 80.300 E (10)
Maximum observed intensity VI (10). Also see 11, 12.

08 February 1900 - Coimbatore area, Tamil Nadu, M? 6.0 (13)
10.800 N, 76.800 E (1)
Known as the Coimbatore earthquake, it was felt over a large section of south India and is the largest event during the historical period.

10 September 1938 - Gulf of Mannar, M? 5.8 (3)
07.50 N, 79.00 E (3)
Maximum observed intensity VII (3).

29 July 1972 - Coimbatore area, Tamil Nadu, Mb 5.0 (2) .
11.000 N, 77.000 E, OT=04:30:00 UTC (2)
Maximum observed intensity VI (3). This event was centred in the eastern section of the city of Coimbatore.

06 December 1993 - Gulf of Mannar, Mb 5.2, Ms 4.7 (5)
06.818 N, 78.301 E, D=010.0 kms OT=20:54:45 UTC (5)
Felt in Colombo, Sri Lanka.

26 September 2001 - Off the coast of Puducherry, Mw 5.5
11.984 N, 80.225 E, D=010.0 kms, OT=14:56:55 UTC
A moderate earthquake occurred in the Bay of Bengal, off the coast of the union territory of Puducherry, on 25 September 2001 at 20:26 PM local time resulting in three deaths and minor damage to property in Puducherry and coastal Tamil Nadu.  It had a magnitude of Mw=5.5.

26 December 2004 - Sumatra-Andaman Earthquake, Mw 9.1
03.298 N, 95.778 E, D=010.0 kms, OT=00:58:50 UTC
A "very great" earthquake struck the North Indian Ocean & the Bay of Bengal at 00:58 UTC on 26 December 2004. 2,30,210 people were are estimated to have been killed in the Indian Ocean-wide tsunami generated by this earthquake, including at least 8,010 in Tamil Nadu and 599 in Puducherry. Most deaths in Tamil Nadu occurred in the district of Nagapattinam.

7 June 2008 - Palar Valley region, M?=3.8
12.800 N, 78.800 E, D=033.0 kms, OT=18:05:23 UTC
A mild earthquake occurred in the Palar Valley region in Tamil Nadu, on 7 June 2008 at 23:35 PM local time. It had a magnitude of M?=3.8 and was felt in many parts of Vellore district.

12 August 2011 - Ariyalur area, Tamil Nadu, M?=3.5
11.100 N, 79.100 E, D=033.0 kms, OT=06:06:32 UTC
A mild earthquake occurred in the Kaveri basin in Ariyalur district, Tamil Nadu on 12 August 2011 at 11:36 AM local time in India. It had a magnitude of M?=3.5 and was felt in several districts in southern Tamil Nadu. It was blamed for one death and minor damage in the districts of Kudalur, Perambalur, Tiruchirapalli and Villupuram.