What is an earthquake?

An earthquake refers to shaking of the earth due to sudden slip of two blocks (tectonic plates) of the earth or when these plates suddenly slip past one another on a fault. Fault or fault plane is the surface where the plates or blocks slip suddenly.

How an Earthquake occurs?

The Earth's crust is made of tectonic plates. These plates keep moving slowly. Sometimes, they get stuck at their edges due to friction. When the pressure for movement overcomes the friction, energy is released in the form of waves or vibrations that travel through the earth's crust and shakes the earth. So, in short, we can say that the shaking of Earth due to a sudden, rapid release of energy in the form of vibrations is called an earthquake.

The location or point below the surface of the earth where the earthquake starts is called hypocentre and the location directly above the hypocentre on the surface of the earth is called the epicentre.

List of Earthquakes in India

Many devastating earthquakes occurred in India in the past. Some of which are listed below:

1. Gujarat Earthquake (2001)
2. Bihar Earthquake (1934) or Bihar-Nepal Earthquake
3. Maharashtra earthquake (1993)
4. Assam earthquake (1950)
5. Uttarkashi earthquake (1991)
6. Jabalpur earthquake (1997)
7. Sikkim Earthquake (2011)
8. Indian Ocean earthquake (2004)
9. Kashmir earthquake (2005)
10. Andaman & Nicobar earthquake (1941)
11. Kinnaur Earthquake (1975)
12. Koynanagar earthquake (1967)
13. Kangra earthquake (1905)
14. Anjar earthquake (1956)
15. Chamoli earthquake (1999)

1) Gujarat Earthquake (2001)

An earthquake of 7.7 magnitude on the Richter scale hit the Gujarat state of India on 26 January 2001. It occurred at 8:40 am in the morning and lasted for around two minutes. Due to high intensity, it was felt throughout north-western India and some regions of the neighbouring country Pakistan.

Many villages and towns were destroyed in this disaster and over 20,000 people lost their lives. Bhuj was destroyed the most as it was close to the epicentre. Besides this, the famous temple of Swaminarayan in the Bhuj was also damaged partially in this natural calamity.

2) Bihar Earthquake (1934) or Bihar-Nepal Earthquake

It is one of the most devastating quakes in the history of India. It hit the Bihar on 15 January 1934. Its magnitude was recorded 8.1 on the Richter scale and more than 30000 people lost their lives in this disaster. The epicentre of this quake was located in eastern Nepal and its intensity was so high that it was felt even in Kolkata that was 600 km far from the epicentre.

It mostly affected the northern Bihar and adjoining areas of Nepal. The worst affected areas in the quake were Munger, Purnea, Champaran and Muzaffarpur in Bihar and Kathmandu, Patan, and Bhaktapur in Nepal.

3) Maharashtra Earthquake (1993)

Maharashtra earthquake is also known as Latur earthquake. It occurred at 3:56 am on 30 September 1993 in the Maharashtra state of India. It was measured 6.4 on the Richter scale and its epicentre was located in Killari village at Latur district. Its hypocentre was only 10 km deep, which is relatively shallow due to which shock waves caused more damage.

Over 20,000 people died in this quake and the most affected regions were Latur and Osmanabad. Besides this, around 52 villages were destroyed in this catastrophe. The National Disaster Management Authority (NDMA) was established after this natural calamity.

4) Assam Earthquake (1950)

Assam earthquake is one of the most devastating quakes of the 20^th century. It is also known as the Medog earthquake or Assam-Tibet earthquake. It occurred at 7:39 pm on 15 August 1950 with a magnitude of 8.6 on the Richter scale. Its epicentre was situated at Rima in Tibet and it severely affected Tibet and Assam both. Around 5000 people were died in this quake out of which 1500 people were from Assam alone.

5) Uttarkashi Earthquake (1991)

Uttarkashi earthquake is also known as the Garhwal earthquake. It occurred at 2:53 am on 20 October 1991 in the Garhwal Himalayas in northern India. Its intensity was measured 6.1 on the Richter scale by the Indian Meteorological Department (IMD) on the basis of body wave data. As per IMD, its epicentre was nearby Almora, at a distance of around 160 km from Uttarkashi.

It mainly affected the Uttarkashi, Tehri, and Chamoli districts in the state of Uttarakhand. As per the official information, 307,000 people living in 1294 villages were affected out of which 768 died and around 5000 were injured. In addition, it claimed over 3000 livestock. Its vibrations were felt up to New Delhi, the capital city of India.

6) Jabalpur Earthquake (1997)

Jabalpur earthquake occurred at 4:21 am in the morning on 22 May 1997 in the district of Jabalpur in the Madhya Pradesh state of India. Its epicentre was close to Koshamghat village. As per the Dr V. Subramanyan, a geologist, the cause of this quake was the movement on the Narmada fault.

The districts that were severely hit by this quake were Jabalpur, Seoni, Chhindwara, and Mandal. Over 30 people died. Besides this, 887 villages were affected due to this catastrophe including 8,546 houses destroyed and around 52,690 houses were damaged partially. Furthermore, longitudinal ground cracks were also observed in some regions of the affected districts.

7) Sikkim Earthquake (2011)

Sikkim Earthquake is also known as the 2011 Himalayan earthquake. It occurred at 6:10 pm on 18 September 2011 in the Kanchenjunga Conservation Area close to the Sikkim and Nepal border. Its magnitude was found 6.9 on the Richter scale and its epicentre was located close to Sikkim-Nepal border around 70 km northwest of Gangtok, Sikkim.

Its impact was felt across north-eastern India including Bhutan, Nepal, southern Tibet and Bangladesh. Around 110 people lost their lives in this quake most of them belonged to Sikkim. This earthquake occurred just a few days after Sonipat district of Haryana was hit by a 4.2 magnitude quake.

8) Indian Ocean Earthquake (2004)

Indian Ocean earthquake is also known as the Boxing Day Tsunami and also called Sumatra-Andaman earthquake by the scientists. It occurred at 07:58 am on 26 December 2004. Its epicentre was off the west coast of northern Sumatra, Indonesia. It was an undersea megathrust earthquake that was measured 9.1-9.3 on Mercalli intensity scale. Its epicentre was located between mainland Sumatra and Simeulue.

The reason for this quake was found to be a split alongside the fault between the Burma and India plate. The underwater seismic activity caused tsunami waves of up to 100ft in height. Countries adjacent to the Indian Ocean were affected adversely and over 2 lakh people were killed in this tsunami.

9) Kashmir Earthquake (2005)

Kashmir earthquake occurred at 8:50 am on 8 October 2005 and was measured 7.6 on the Richter scale. Its epicentre was found located at the POK in Pakistan. Apart from India and Pakistan, it was also felt in China, Tajikistan and Afghanistan. More than 80,000 people were killed, around 70,000 were injured and around 3 million people were displaced due to this catastrophe. However, over 65 per cent of the casualties were reported only in Muzaffarabad, Pakistan.

One of the major reasons for this quake was the unstable seismicity in the area of POK. The data collected from the satellite showed that mountains had risen by a few meters after this incident and it was believed that it could be the consequence of the rising Himalayas.

10) Andaman & Nicobar Earthquake (1941)

The 1941 Andaman earthquake was one of the strongest quakes in the Andaman & Nicobar of India. It occurred on 26 June 1941 at 11:52 pm. It was measured 8.1 Mw in magnitude. Its hypocentre was not very deep so strong shaking of the ground was felt throughout the Islands including the eastern coast of India, Sri Lanka and Colombo.

Furthermore, the earthquake generated a tsunami in the Bay of Bengal and the Andaman Sea that also affected the Indian east coast and adjoining communities. The exact number of causalities and the extent of damage is not clear as most of Southeast Asia was facing the turmoil of World War II in that time. Still, it is believed that around 8,000 people died in this quake and tsunami in the Andaman Islands and neighbouring countries like Thailand, Myanmar, Sri Lanka and Bangladesh.

11) Kinnaur Earthquake (1975)

Kinnaur earthquake occurred at 08:02 am on 19 January 1975. It magnitude was measured 6.8 on the surface wave magnitude scale whereas on Mercalli intensity scale its magnitude was found 9. Due to its high intensity, it caused severe destruction in Himachal Pradesh, India.

Its epicentre was located in the district of Kinnaur in the south-eastern part of Himachal Pradesh and caused around 50 casualties. This quake caused damage to the Hindustan-Tibet road and affected various monasteries, buildings, construction work in the state. Many fissures were developed at the epicentre.

12) Koynanagar Earthquake (1967)

Koynanagar earthquake occurred on 11 December 1967 close to Koyna Dam in the south-western region of India. Its magnitude was measured 6.5 on the surface wave magnitude scale. The Koyna dam, which is 338 feet high and 2800 feet long, suffered structural damage as it was in the epicentre-region of this quake.

Its epicentre was close to Koshamghat village. As per the Dr V. Subramanyan, a geologist, the cause of this quake was the movement on the Narmada fault.

The districts that were severely hit by this quake were Jabalpur, Seoni, Chhindwara, and Mandal. Around 200 people were killed, 887 villages were affected due to this catastrophe including 8,546 houses destroyed and around 52,690 houses were damaged partially. Furthermore, longitudinal ground cracks were also observed in some regions of the affected districts.

13) Kangra Earthquake (1905)

Kangra earthquake occurred in Kangra Valley at 6:19 am in the morning on 4 April 1905. As of now, this region belongs to Himachal Pradesh, India. On the surface wave magnitude scale this quake was measured 7.8 and around 20,000 people died in this quake and around 53,000 livestock were also lost or injured. The impact of this quake felt over 4.2 lakh sq. km. of land.

Besides this, lots of buildings and homes were damaged in the Kangra, Dharamshala and Mcleodganj. Many historical structures like Kangra fort, Kangra temple and Sidhnath temple were destroyed completely, however, the Baijanth temple was damaged partially. The cost of recovering from the damage due to this catastrophe was around 3 million rupees in that time (1905).

14) Anjar Earthquake (1956)

Anjar earthquake occurred at 03:32 on 21 July 1956. It was measured 6.1 on the surface wave magnitude scale and on the Mercalli intensity scale its maximum intensity was found to be IX. The maximum destruction was caused in the Anjar town in Kutch district of Gujarat. The other affected towns were Kera, Bhuj, Bhachau, Kandla and Gandhidham.

Its epicentre was found between Anjar and Bhadresar. The maximum damage occurred over 2000 sq. km. of land and the cause of this catastrophe was reverse faulting. As per govt. records, around 250 people lost their lives, and over 3000 houses of 25 villages developed huge cracks.

15) Chamoli Earthquake (1999)

Chamoli earthquake occurred on 29 March in the Chamoli district of the Uttarakhand. It was one of the strongest earthquakes that hit the foothills of Himalayas. Its magnitude was recorded 6.8 on the Richter scale. In addition to Chamoli, it affected various other districts of Uttarakhand such as Tehri Garhwal, Rudraprayag, Uttarkashi, Bageshwar and Pauri Garhwal.

Chamoli and Rudraprayag faced the maximum destruction. It was also felt in Delhi, Shimla, Haridwar, Saharanpur, Bijnor, Meerut, etc. Around 103 people died lost their lives in this quake and around 50,000 houses were damaged and around 2000 villages were affected in this catastrophe.