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Major Areas :: Disaster Managment :: Earthquake


Earthquake is one of the most destructive natural hazard. They may occur at any time of the year, day or night, with sudden impact and little warning. They can destroy buildings and infrastructure in seconds, killing or injuring the inhabitants. Earthquakes not only destroy the entire habitation but may de-stabilize the government, economy and social structure of the country.

Earthquakes are the manifestations of sudden release of strain energy accumulated in the rocks over extensive periods of time in the upper part of the Earth.

Seismology (derived from Greek word Seismos meaning Earthquake and Logos meaning science) is the science of Earthquakes and related phenomena.

Seismograph/ Seismogram
Seismograph is an instrument that records the ground motions. Seismogram is a continuous written record of an earthquake recorded by a seismograph.

Seismic Zonation Map of India

Seismic Zonation map of a country is a guide to the seismic status of a region and its susceptibility to earthquakes. India has been divided into five zones with respect to severity of earthquakes. Of these, Zone V is seismically the most active where earthquakes of magnitude 8 or more could occur recent strong motion observations around the world have revolutionized thinking on the design of engineering structures, placing emphasis also on the characteristics of the structures themselves it should be realized that in the case of shield type earthquakes, historic data are insufficient to define zones because recurrence intervals are much longer than the recorded human history this may often give a false sense of security. Occurrence of the damaging earthquake at Latur, falling in zone I is a typical example of this situation.

Cause of Earthquake :

The earth’s crust is a rocky layer of varying thickness ranging from a depth of about 10kilometers under the sea to 65 kilometers under the continents. The crust is not one piece but consists of portions called ‘plates’ which vary in size from a few hundred to thousands of kilometers. The ‘theory of plate tectonics’ holds that theplates ride up on the more mobile mantle,and are driven by some yet unconfirmed mechanisms, perhaps thermal convection currents. When these plates contact each other, stress arises in the crust. These stresses can be classified according to the type of movement along the plate’s boundaries:
a) pulling away from each other,
b) pushing against one another and
c) sliding sideways relative to each other.

All these movements are associated with earthquakes.The areas of stress at plate boundaries which release accumulated energy by slipping or rupturing are known as 'faults'. The theory of 'elasticity' says that the crustis continuously stressed by the movement of the tectonic plates; it eventually reaches a point of maximum supportable strain. A rupture then occurs along the fault and the rock rebounds under its own elastic stresses until the strain is relieved. The fault rupture generates vibration called seismic (from the Greek 'seismos' meaning shock or earthquake) waves, which radiates from the focus in all directions. The point of rupture is called the 'focus' and may be located near the surface or deep below it. The point on the surface directly above the focus is termed as the  epicenter' of the earthquake


It is a quantity to measure the size of an earthquake and is independent of the place of the observation.

Richter Scale:

The local magnitude is defined as the logarithm of the maximum amplitude measured in microns on a seismogram written by Wood-Anderson seismograph with free period of 0.8 second, magnification of 2,800, damping factor of 0.8 calculated to be at a distance of 100 kms. The relative size of events is calculated by comparison to a reference event of ML=0,using the formula, ML=log A-log Ao

        where A is the maximum trace amplitude in micrometer recorded on a standard seismograph and Ao is a standard value which is a function of epicentral distance (Δ) in kilometers.

Classification of earthquakes
Category Magnitude on Richter Scale
Slight Upto 4.9
Moderate 5.0 to 6.9
Great 7.0 to 7.9
Very Great 8.0 and more

Source: www.imd.gov.in
India has witnessed some of the most devastating earthquakes during the last century like the one in Kangra (1905), Bihar-Nepal (1934) and in Assam (1950). In the recent past, earthquakes have caused havoc in Uttarkashi (1991), Latur (1993), Jabalpur (1997), Chamoli (1999) and in Bhuj (2001).
On 26th January 2001, India experienced one of the worst earthquakes in recent times. Measuring 6.9 on the Richter scale, the earthquake caused incalculable damage not just to its epicenter, Bhuj but also to other towns of the district of Kutch and to about 500 villages out of the total of 900 villages. The reported damage to property in Gujarat was about Rs.21, 000crore and the number of human lives lost were about 14,000. Of these, more than 500 deaths were reported from Ahmedabad, situated at a distance of about 350 kms from Bhuj. In the same city, close to 150 multi-storied buildings crumbled down. Cities far away from the epicenter, like Surat, too reported damage to property.


Year of occurrence
Place of occurrence Intensity   Others
1618 Bombay - - 2000 lives lost
1720 Delhi 6.5 - Some lives lost
1737 Bengal - - 300,000 lives lost
1803 Mathura 6.5 - The shock felt up to Calcutta.
1803 Kumaon 6.5 - Killed 200-300 people.
1819 Kutchch 8.0 XI Chief towns of Tera, Kathara and Mothala razed to the ground.
1828 Srinagar 6.0 - 1000 people killed.
1833 Bihar 7.7 X Hundreds of people killed
1848 Mt.Abu, Rajasthan 6.0 - Few people killed
1869 Assam 7.5 - Affected an area of 2,50,000 Sq. miles.
1885 Srinagar 7.0 - Kamiarary area destroyed.
1897 Shillong 8.7 XII Wide spread destruction in Shillong.
1905 Himachal Pradesh 8.0 XI Thousands of people killed.
1906 Himachal Pradesh 7.0 - Heavy damage.
1916 Nepal 7.5 - All houses collapsed at Dharchulla.
1918 Assam 7.6 - Heavy damage.
1930 Dhubri, Meghalaya 7.1 IX Heavy damage in Dhubri.
1934 Bihar, Nepal 8.3 XI Large number of border area people killed.
1935 Quetta (in Pakistan) 7.5 IX 25,000 people killed
1941 Andaman 8.1 X Very heavy damage.
1947 Dibrugarh 7.8 - Heavy damage.
1950 Assam 8.6 XII Heavy damage to life and property.
1952 NE India 7.5 - Heavy damage.
1956 Bulandshahar, U.P. 6.7 VIII Many people killed
1956 Anjar, Gujarat 7.0 VIII Hundreds of people killed
1958 Kapkote, U.P. 6.3 VIII Many people killed
1967 Koyna, 6.1 VIII Koyna Nagar razed.
1969 Bhadrachalam 6.5 1 Heavy damage.
1986 Dharamshala (H.P) 5.7 VIII Lots of damage.
1988 Assam 7.2 IX Few people killed
1988 Bihar- Nepal 6.5 VIII Large number of people killed.
1991 Uttarkashi 6.6 VIII Lots of damage to life and property.
1993 Latur 6.4 VIII Heavy damage to life and property about, 000 people killed.
1997 Jabalpur 6.0 VIII Lots of damage to property, about 39 lives lost.
1999 Chamoli 6.8 VIII Lots of damage to property about 100 people lost lives.
2001 Bhuj 6.9 X Huge devastation, about ~ 14000 people lost lives


India has had a long history of earthquake occurrences. About 65% of the total area of the country is vulnerable to seismic damage of buildings in varying degrees. The most vulnerable areas, according to the present seismic zone map of India, are located in the Himalayan and sub-Himalayan regions, Kutch and the Andaman and Nicobar Islands. Depending on varying degrees of seism city, the entire country can be divided into the following seismic regions:

  • Kashmir and Western Himalayas - Covers the states of Jammu and Kashmir, Himachal Pradesh and sub-mountainous areas of Punjab
  • Central Himalayas - Includes the mountain and sub-mountain regions of Uttar Pradesh and the sub-mountainous parts of Punjab
  • North-east India - Comprises the whole of Indian territory to the east of north Bengal
  • Indo-Gangetic basin and Rajasthan - This region comprises of Rajasthan, plains of Punjab, Haryana, Uttar Pradesh and West Bengal
  • Cambay and Rann of Kutch
  • Peninsular India, including the islands of Lakshwadeep
  • The Andaman and Nicobar Islands


For better understanding of all the possibilities of earthquake risk reduction, it is important to classify them in terms of the role that each one of them could play. Therefore, in the pre-earthquake phase, preparedness, mitigation and prevention are concepts to work on. Post-disaster, immediate rescue and relief measures including temporary sheltering soon after an earthquake until about 3 months later and re-construction and re-habilitation measures for a period of about six months to three years need to follow. To encapsulate, the most effective measures of risk reduction are pre-disaster mitigation, preparedness and preventive measures to reduce vulnerability and expeditious, effective rescue and relief actions immediately after the occurrence of the earthquake. Depending upon the calamity and its consequences, strategies can also be divided into long term (five to fifteen years), medium term (one to five years) and short term (to be taken up immediately in high risk areas). Since it has been realized that earthquakes don't kill people but faulty constructed buildings do, the task of reducing vulnerability of structures and buildings will be the key to earthquake risk reduction. Also, pre-disaster preparedness through a post-earthquake response plan, including training of the concerned personnel in various roles, is considered essential for immediate and effective response after an earthquake occurrence. The major action points are highlighted in the following paragraphs.

Long-term measures

  • Re-framing buildings' codes, guidelines, manuals and byelaws and their strict implementation. Tougher legislation for highly seismic areas.
  • Incorporating earthquake resistant features in all buildings at high-risk areas.
  • Making all public utilities like water supply systems, communication networks, electricity lines etc. earthquake-proof. Creating alternative arrangements to reduce damages to infrastructure facilities.
  • Constructing earthquake-resistant community buildings and buildings (used to gather large groups during or after an earthquake) like schools, dharamshalas, hospitals, prayer halls, etc., especially in seismic zones of moderate to higher intensities.
  • Supporting R&D in various aspects of disaster mitigation, preparedness and prevention and post-disaster management.
  • Evolving educational curricula in architecture and engineering institutions and technical training in polytechnics and schools to include disaster related topics.

Medium term measures

  • Retrofitting of weak structures in highly seismic zones.
  • Preparation of disaster related literature in local languages with dos and don'ts for construction.
  • Getting communities involved in the process of disaster mitigation through education and awareness.
  • Networking of local NGOs working in the area of disaster management.

Earthquake Facts & Statistics

Frequency of Occurrence of Earthquakes

Descriptor Magnitude Average Annually 
Great 8 and higher 1 ¹
Major 7 - 7.9 17 ²
Strong 6 - 6.9 134 ²
Moderate 5 - 5.9 1319 ²
Light 4 - 4.9 13,000 (estimated)
Minor 3 - 3.9 130,000 (estimated)
Very Minor 2 - 2.9 1,300,000 (estimated)
¹Based on observations since 1900.
² Based on observations since 1990.

Year-wise description of Earth Quakes

Number of Earthquakes Worldwide for 2000 - 2005. Located by the US Geological Survey National Earthquake Information Center
Magnitude 2000 2001 2002 2003 2004 2005
8.0 to 9.9 1 1 0 1 2 1
7.0 to 7.9 14 15 13 14 14 9
6.0 to 6.9 158 126 130 140 140 116
5.0 to 5.9 1345 1243 1218 1203 1509 1307
4.0 to 4.9 8045 8084 8584 8462 10894 10264
3.0 to 3.9 4784 6151 7005 7624 7937 5782
2.0 to 2.9 3758 4162 6419 7727 6317 3249
1.0 to 1.9 1026 944 1137 2506 1344 20
0.1 to 0.9 5 1 10 134 103 0
No Magnitude 3120 2938 2937 3608 2939 642
Total 22256 23534 27454 31419 * 31199 * 21390
Estimated Deaths 231 21357 1685 33819 284010 1957

List of Some Significant Earthquakes in India

Date Epicenter Location Magnitude
1819 Jun 16 23.6 68.6 Kutch,Gujarat 8.0
1869 Jan 10 25 93 Near Cachar, Assam 7.5
1885 May 30 34.1 74.6 Sopor, J&K 7.0
1897 Jun 12 26 91 Shillongplateau 8.7
1905 Apr 04 32.3 76.3 Kangra, H.P 8.0
1918 Jul 08 24.5 91.0 Srimangal, Assam 7.6
1930 Jul 02 25.8 90.2 Dhubri, Assam 7.1
1934 Jan 15 26.6 86.8 Bihar-Nepalborder 8.3
1941 Jun 26 12.4 92.5 Andaman Islands 8.1
1943 Oct 23 26.8 94.0 Assam 7.2
1950 Aug 15 28.5 96.7 Arunachal Pradesh-China Border 8.5
1956 Jul 21 23.3 7.0 Anjar, Gujarat 7.0
1967 Dec 10 17.37 73.75 Koyna, Maharashtra 6.5
1975 Jan 19 32.38 78.49 Kinnaur, Hp 6.2
1988 Aug 06 25.13 95.15 Manipur-Myanmar Border 6.6
1988 Aug 21 26.72 86.63 Bihar-Nepal Border 6.4
1991 Oct 20 30.75 78.86 Uttarkashi, Up Hills 6.6
1993 Sep 30 18.07 76.62 Latur - Osmanabad, Maharashtra 6.3
1997 May 22 23.08 80.06 Jabalpur, MP 6.0
1999 Mar 29 30.41 79.42 Champoli, UP 6.8
2001 Jan 26 23.40 70.28 Bhuj, Gujarat 6.9

www.imd.gov.in/section/seismo/static/welcome.htm (Seismological activities)