What is Earthquake? Why does it happen in India?| Geography

An earthquake is a natural phenomenon that occurs when two blocks of the Earth's crust suddenly slip past one another along a fault line, causing the ground to shake or vibrate. Earthquakes can happen anywhere in the world, but are most common in areas where there are tectonic plate boundaries, such as the Pacific Ring of Fire.

Credit: National Geographic Society

The energy released by an earthquake is measured on the Richter scale, which is a logarithmic scale that ranges from 1 to 10. Each increase in number represents a tenfold increase in the amplitude of the seismic waves generated by the earthquake, and a 32-fold increase in the energy released.

Earthquakes can cause a wide range of damage, depending on their magnitude and the location of the epicenter. In areas with poor building codes and construction practices, earthquakes can be particularly devastating, resulting in loss of life, injuries, and extensive damage to buildings and infrastructure.

Earthquake in India:

Seismic Zones in India

Just the shaking of the ground, an earthquake happens naturally, as a result of energy being released, which makes waves move in all directions. Seismic waves produced by the vibration of the Earth are detected by seismographs.

Moderate-sized earthquakes occur daily, but powerful tremors that inflict extensive destruction are less frequent. Earthquakes are more frequent around plate boundaries, particularly along convergent boundaries. In the area where the Indian Plate and the Eurasian Plate clash, such as the Himalayan region, more earthquakes occur.

Although India's peninsular region is thought to be a stable area, earthquakes are occasionally felt on the edges of smaller plates. Indian seismologists have divided India into four seismic zones: Zone II, Zone III, Zone IV, and Zone V.

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 Earthquake:

There are different types of earthquakes based on their causes, characteristics, and the geological features where they occur. Here are some of the common types of earthquakes:

1. Tectonic earthquakes: These are the most common type of earthquake and occur when two tectonic plates in the Earth's crust suddenly move past each other, releasing energy in the form of seismic waves.

2. Volcanic earthquakes: These earthquakes occur near active volcanoes and are caused by the movement of magma or the collapse of the volcanic edifice.

3. Collapse earthquakes: These earthquakes occur in underground mines and other underground spaces and are caused by the collapse of the roof or walls of the underground space.

4. Induced earthquakes: These earthquakes are caused by human activities such as the construction of large dams, underground nuclear tests, and the extraction of oil and gas.

5. Deep earthquakes: These earthquakes occur at depths of more than 300 km below the Earth's surface and are caused by the movement of tectonic plates in the Earth's mantle.

6. Megathrust earthquakes: These are the most powerful earthquakes and occur at subduction zones where one tectonic plate is forced under another. These earthquakes are often accompanied by tsunamis.

7. Aftershock earthquakes: These are smaller earthquakes that occur after a larger earthquake and are caused by the adjustment of the Earth's crust following the main earthquake.

Earthquake zones in India:

India is a seismically active country, and the Indian subcontinent is prone to earthquakes due to its location on the boundary of the Indian Plate and the Eurasian Plate. Indian seismologists have divided the country into four seismic zones based on the intensity and frequency of earthquakes in those regions:

1. Zone II: This zone is considered to have the lowest seismic activity and includes the northeastern states, parts of Jammu and Kashmir, Himachal Pradesh, and the Andaman and Nicobar Islands.

2. Zone III: This zone is considered to have moderate seismic activity and includes the states of Bihar, Chhattisgarh, Gujarat, Jharkhand, Madhya Pradesh, Maharashtra, Orissa, Rajasthan, Uttar Pradesh, and West Bengal.

3. Zone IV: This zone is considered to have high seismic activity and includes the states of Assam, Meghalaya, Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura, Sikkim, parts of Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Bihar, and West Bengal.

4. Zone V: This zone is considered to have the highest seismic activity and includes the entire Himalayan region, parts of Jammu and Kashmir, Himachal Pradesh, Uttar Pradesh, Bihar, and the Rann of Kutch in Gujarat.

The seismic zones in India provide a basis for earthquake-resistant building codes and disaster management planning in the country.

Reasons for Earthquake in India:

India is located on the boundary of the Indian Plate and the Eurasian Plate, which makes it a seismically active region. Here are some of the causes of earthquakes in India:



Tectonic Earthquake






Volcanic Earthquake







1. Tectonic activity: The movement of tectonic plates is the primary cause of earthquakes in India. India is situated on the boundary of the Indian Plate and the Eurasian Plate, which collide with each other, causing earthquakes. The Himalayan region, which is one of the most seismically active regions in the world, is also a result of tectonic activity.

2. Volcanic activity: Although there are no active volcanoes in India, the Deccan Traps, a large volcanic plateau in western and central India, was formed by volcanic activity. Some earthquakes in this region may be caused by volcanic activity.

3. Induced earthquakes: Human activities such as the construction of large dams, underground nuclear tests, and the extraction of oil and gas can cause induced earthquakes. For example, the Koyna earthquake of 1967, which was one of the most powerful earthquakes in India, was caused by the construction of the Koyna Dam in Maharashtra.

4. Geological features: The geological features of a region can also cause earthquakes. For example, the earthquakes in the northeastern region of India are caused by the subduction of the Indian Plate beneath the Burma Plate.

5. Plate boundary zones: The plate boundary zones in India are particularly prone to earthquakes. For example, the Himalayan region, which is located on the boundary of the Indian Plate and the Eurasian Plate, experiences frequent earthquakes due to the collision of these two plates.

These are some of the major causes of earthquakes in India. Understanding the causes of earthquakes can help in earthquake prediction and preparedness.

Impact of Earthquake in India:

Earthquakes can have a significant impact on India, both in terms of human and economic losses. Here are some of the impacts of earthquakes in India:

1. Loss of life and injuries: Earthquakes can cause the loss of human lives and injuries. In some cases, earthquakes can result in a high number of casualties. For example, the Bhuj earthquake in 2001 resulted in the deaths of more than 20,000 people.

2. Damage to buildings and infrastructure: Earthquakes can cause extensive damage to buildings and infrastructure such as roads, bridges, and dams. This can disrupt the daily lives of people and impact the economy.

3. Economic losses: Earthquakes can result in economic losses due to damage to buildings, infrastructure, and loss of productivity. The cost of rebuilding and repairing damaged structures and infrastructure can be significant.

4. Displacement of people: Earthquakes can displace people from their homes and communities, resulting in the need for emergency shelters, food, and other necessities.

5. Environmental impacts: Earthquakes can also have environmental impacts such as landslides, soil liquefaction, and changes in groundwater levels.

6. Social impacts: Earthquakes can have social impacts such as trauma, fear, and mental health issues among affected communities.

India has experienced several significant earthquakes in the past, and the country has taken measures to prepare for and mitigate the impacts of earthquakes. These measures include building codes, disaster management plans, and early warning systems. However, the impacts of earthquakes can still be severe, and ongoing efforts are needed to minimize their impact.