Earthquakes in India, Types, Zones, Causes and Impacts

An earthquake is just the shaking of the ground. It happens naturally. It happens as a result of energy being released, which makes waves move in all directions. When an earthquake occurs, the Earth vibrates, producing seismic waves that are detected by seismographs.

Every day, moderate-sized earthquakes take place. On the other hand, powerful tremors that inflict extensive destruction are less frequent. Around plate boundaries, particularly along convergent boundaries, earthquakes are more frequent. More earthquakes occur in the area of India where the Indian Plate and the Eurasian Plate clash. Consider the Himalayan region, for instance.

Earthquakes in India

Earthquakes in India are primarily caused by the movement of the Indian tectonic plate, which is colliding with the Eurasian plate. India’s peninsular region is thought to be a stable area. On occasion, though, earthquakes are felt on the edges of smaller plates. The 1967 Koyna earthquake and the 1993 Latur earthquake are two examples of earthquakes that occurred in peninsular areas.

India is divided into four seismic zones (II, III, IV, V) based on the level of seismicity:

• Zone II: Low seismicity
• Zone III: Moderate seismicity
• Zone IV: High seismicity
• Zone V: Very high seismicity (includes areas like the Himalayan region, northeastern states, Kutch, and Andaman & Nicobar Islands)

As can be seen, zones V and IV are assigned to the entire Himalayan region as well as the states of North-East India, Western and Northern Punjab, Haryana, Uttar Pradesh, Delhi, and portions of Gujarat. A significant chunk of the peninsular region is in the low-risk zone, while the northern lowlands and western coastal regions continue to be in the moderate hazard zone.

Types of Indian Earthquakes

In India, earthquakes can be categorized based on their origins and the tectonic settings. Here are the main types:

Type of Earthquake	Description	Example/Region
Tectonic Earthquakes	Caused by the movement of Earth’s tectonic plates.
– Interplate Earthquakes	Occur at the boundaries between two tectonic plates.	Himalayan region
– Intraplate Earthquakes	Occur within a tectonic plate.	Latur earthquake (1993), Maharashtra
Volcanic Earthquakes	Associated with volcanic activity due to the movement of magma beneath the Earth’s surface.	Andaman and Nicobar Islands
Induced Earthquakes	Caused by human activities such as mining, reservoir filling, geothermal energy extraction, and oil extraction.
– Reservoir-Induced	Earthquakes induced by the filling of large dams.	Koyna earthquake (1967), Maharashtra
Collapse Earthquakes	Caused by the collapse of underground caverns or mines. Usually localized and of low magnitude.	Mining areas
Explosion Earthquakes	Caused by explosions, such as nuclear tests or large chemical explosions.	Nuclear tests in Pokhran, Rajasthan

1. Tectonic Earthquakes

These are the most common types of earthquakes in India and occur due to the movement of the Earth’s tectonic plates. They can be further classified into:

• Interplate Earthquakes: Occur at the boundaries between two tectonic plates. For example, the Himalayan region experiences frequent interplate earthquakes due to the collision between the Indian and Eurasian plates.
• Intraplate Earthquakes: Occur within a tectonic plate rather than at its boundary. The Latur earthquake (1993) in Maharashtra is an example.

2. Volcanic Earthquakes

These are associated with volcanic activity and are relatively rare in India. They occur due to the movement of magma beneath the Earth’s surface. The Andaman and Nicobar Islands, which have some volcanic activity, can experience such earthquakes.

3. Induced Earthquakes

These are caused by human activities such as mining, reservoir-induced seismicity (due to the filling of large dams), geothermal energy extraction, and oil extraction. Examples include:

• Reservoir-Induced Seismicity: The Koyna earthquake (1967) in Maharashtra is believed to have been induced by the filling of the Koyna dam reservoir.

4. Collapse Earthquakes

These occur due to the collapse of underground caverns or mines. They are usually localized and of low magnitude.

5. Explosion Earthquakes

These are caused by explosions, such as nuclear tests or large chemical explosions. For instance, nuclear tests conducted in Pokhran, Rajasthan, generated minor seismic activity.

Earthquake Zones in India

Here’s a complete List of All Zones of Earthquakes in India:

The zones are distinguished using Modified Mercalli (MM) intensity, which evaluates the impact of earthquakes. However, the seismic zoning map was updated following the Killari earthquake in Maharashtra in 1993, merging the low danger zone, or Seismic Zone I, with Seismic Zone II. Zone I is therefore excluded from the mapping.

Zone II

It falls under the low-intensity category. It covers 40.93% of the nation’s land area. Along with the Karnataka Plateau, it also encompasses the peninsula region.

Zone III

This region is moderately intense. It covers 30.79 per cent of the nation’s area. The state is made up of Kerala, Goa, and the Lakshadweep Islands, as well as portions of Punjab, Rajasthan, Madhya Pradesh, Bihar, Jharkhand, Chhattisgarh, Maharashtra, Odisha, and Tamil Nadu.

Zone IV

A high-intensity zone is what it is called. It covers 17.49% of the land area of the nation. It encompasses the remaining portions of Jammu & Kashmir, Himachal Pradesh, the National Capital Territory (NCT) of Delhi, Sikkim, the northern portions of Uttar Pradesh, Bihar, West Bengal, the western coast of Maharashtra, and Rajasthan.

Zone V

It falls under the category of an extremely severe zone. It covers 10.79 per cent of the land area of the nation. It also covers a region of North Bihar, Himachal Pradesh, Uttarakhand, the Rann of Kutch in Gujarat, and the Andaman and Nicobar Islands.

Major Earthquakes in India List

Some of the devastating earthquakes have affected India. More than 58.6% of Indian Territory is vulnerable to earthquakes of moderate to very high intensity. Some of India’s most significant earthquakes include:

• Cutch Earthquake (1819) which was 8.3 magnitude
• Assam Earthquake (1897)
• Bihar-Nepal Earthquake (1934) of 8.4 magnitude
• Koyna Earthquake (1967) of 6.5 magnitude
• Uttarkashi (1991) of 6.6 magnitude
• Killari (1993) of 6.4 magnitude
• Bhuj (2001) of 7.7 magnitude
• Jammu Kashmir (2005)

Key Regions Prone to Different Types of Earthquakes

Region	Type of Earthquake	Description
Himalayan Region	Tectonic (Interplate)	Frequent earthquakes due to the collision of the Indian and Eurasian plates.
Northeastern India	Tectonic (Interplate)	Complex tectonic interactions cause frequent earthquakes.
Western India (Kutch)	Tectonic (Intraplate)	hquake (2001).
Peninsular India	Tectonic (Intraplate)	Generally stable but can experience intraplate earthquakes like Latur (1993).
Andaman & Nicobar Islands	Tectonic & Volcanic	Prone to both tectonic and volcanic earthquakes.

List of Major Earthquakes in India Year-wise for UPSC

• 2015 India/Nepal Earthquake
• 2011 Sikkim Earthquake
• 2005 Kashmir Earthquake
• 2004 Indian Ocean Earthquake
• 2001 Bhuj Earthquake
• 1999 Chamoli Earthquake
• 1997 Jabalpur Earthquake
• 1993 Latur Earthquake
• 1991 Uttarkashi Earthquake
• 1941 Andaman Islands Earthquake
• 1975 Kinnaur Earthquake
• 1967 Koynanagar Earthquake
• 1956 Anjar Earthquake
• 1934 Bihar/Nepal Earthquake
• 1905 Kangra Earthquake

Causes of Earthquakes in India

Avalanches and Landslides

Tremors can cause slope instability and collapse, which can lead to debris falling down the slope and causing landslides, especially in hilly areas. Massive amounts of ice may fall from peaks covered in snow as a result of avalanches brought on by earthquakes. As an illustration, the 2015 Nepal earthquake led to several avalanches on and near Mount Everest.

Landslides and considerable property damage were caused by the Sikkim earthquake of 2011 in particular at the Singik and Upper Teesta hydroelectric projects.

Floods

Flash floods and failures of dams and reservoirs could result from the earthquake. Flooding could result from avalanches and slides impeding the river’s flow. The 1950 Assam earthquake produced a barrier in the Dihang River as a result of the buildup of enormous debris, resulting in flash floods in the upstream region.

Tsunami

When an ocean basin is disturbed and a significant amount of water is displaced, waves called tsunamis are created. The seafloor is moved by seismic waves from earthquakes, which can produce large sea waves. On December 26, 2004, an earthquake off the coast of Sumatra caused the Indian Ocean Tsunami.

The Indian plate subducting beneath the Burmese plate is what caused it to happen. Over 2.4 lakh people were killed in the Indian Ocean region and its neighbouring countries. Ten-meter Tsunami waves were produced by an undersea earthquake of magnitude nine during the devastating Tohoku earthquake in Japan in 2011. Due to the destruction of the emergency generators cooling the reactors, a nuclear meltdown occurred, and the radioactive fallout from Fukushima Daiichi became a major global problem.

Impact of Earthquakes in India

Loss of Human Life and Property

Human towns and structures sustain severe damage and destruction as a result of the ground surface deformation brought on by the earth’s crust’s vertical and horizontal movement. a case in point An analysis of the urban devastation caused by the 2015 Nepal earthquake.

The depth of this 7.8-magnitude earthquake was 8.2 kilometres. The Nepal earthquake claimed many lives as a result of unchecked urban expansion, poorly engineered buildings, and unscientifically designed constructions. Urban areas of Kathmandu were badly devastated, causing 8,000 fatalities and a 10 billion dollar economic loss.

Alterations to the River’s Course

The alteration in the river’s course brought on by the obstruction is one of the earthquake’s significant effects.

Fountains of Mud

Mud and boiling water may surface as a result of the earthquake’s tremendous force. The agricultural field was covered in knee-deep mud following the 1934 Bihar earthquake.

Fire Risks

Gas pipelines and electric infrastructure are both harmed by earthquakes. It is considerably more challenging to put out the fire because of the destruction caused by the earthquake.

Mitigation Measures for Earthquakes in India

The National Center for Seismology

Governmental organisations receive earthquake monitoring and hazard reports from a department of the Ministry of Earth Sciences. There are three divisions in it: Geophysical Observation System, Earthquake Hazard and Risk Assessment, and Earthquake Monitoring and services.

National Earthquake Risk Mitigation Project (NERMP)

Enhancing earthquake mitigation programmes’ non-structural and structural components. It aids in lowering susceptibility in high-risk areas. In the areas with strong seismic activity, necessary risk reduction measures are put in place. The project’s assigned agency, NDMA, has created a detailed project report (DPR).

National Building Code (NBC)

It is a comprehensive building code and a national regulation that sets rules for controlling building construction across the nation. The Planning Commission ordered its first 1970 publication, which was later updated in 1983. Following that, three significant amendments—two in 1987 and the third in 1997—were published. The National Building Code of India 2005 replaces the updated NBC (NBC 2005). Meeting the problems presented by natural disasters and adopting current, applicable international best practises are the key characteristics.

Building Materials & Technology Promotion Council (BMTPC)

It takes on projects for life-line structural retrofitting to raise awareness among the populace and various governmental organisations. It sought to assist the general public and policymakers in particular in their efforts to lessen the vulnerability of the thousands of existing public and private structures.

NDMA Guidelines for Earthquakes

In 2007, the NDMA published its comprehensive earthquake recommendations. The rules specify actions that must be taken by State Governments, Central Ministries, and Departments in order to create disaster management plans with a focus on managing earthquake risk. Six pillars make up the fundamental tenet of these principles:

• The building of new structures that is earthquake-resistant.
• Retrofitting and selective seismic strengthening of existing structures.
• Enforcement and regulation.
• Preparation and awareness.
• Building capacity;
• Emergency reaction.

Biggest Earthquakes in India

The devastating Bhuj earthquake of 2001 took place on January 26, 2001, near the Pakistani border in the Indian state of Gujarat. The largest earthquake in India, measuring 8.6 on the Richter scale, struck the India-China region on August 15, 1950. 1530 people perished as a result of the shifting of tectonic plates at a depth of 30 km.

Earthquake in the Indian Ocean

Here are the key points about the 2004 Indian Ocean earthquake and tsunami:

• Magnitude: Between 9.1 and 9.3 on the Richter scale, making it one of the largest earthquakes ever recorded.
• Duration: Faulting lasted between 8.3 and 10 minutes, unusually long for an earthquake of this magnitude.
• Aftershocks: Numerous aftershocks continued for 3 to 4 months after the initial earthquake.
• Energy Release: The earthquake released a massive amount of energy, causing significant geological effects.
• Earth’s Axis Shift: It is believed that the earthquake caused a slight shift in the Earth’s axis due to the redistribution of mass.
• Tsunami Generation: The seismic activity caused vertical movement of the seafloor, displacing a large volume of water and triggering a tsunami.
• Impact: Indonesia was the first and hardest-hit country due to its proximity to the epicenter.
• Casualties: Approximately 170,000 people lost their lives, making it one of the deadliest natural disasters in recorded history.

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