Earthquakes in India| Class 11 Geography Notes

Earthquakes are sudden, violent shaking movements of the Earth’s surface caused by the abrupt release of energy from within the Earth’s crust or upper mantle. They occur along fault lines or tectonic plate boundaries and can range from gentle tremors to catastrophic events capable of causing widespread destruction and loss of life.

Let us learn more about earthquakes in India!

Earthquakes in India| Class 11 Geography Notes

What are Earthquakes?

Earthquakes are sudden, violent shakings or tremblings of the Earth’s surface. They occur when there is a sudden release of energy from inside the Earth. This energy is stored up as rocks underneath the Earth’s surface get slowly bent, squeezed, or twisted over time by the movement of the big tectonic plates that make up the Earth’s crust. When the stress on the rocks becomes too great, they suddenly break or rupture along cracks called faults. This abrupt movement releases the stored-up energy in waves that travel through the Earth’s layers, causing the shaking we feel during an earthquake.

How does an Earthquake occur?

Sometimes earthquakes happen when molten rock (magma) underneath the surface pushes up or when volcanoes erupt, making the surrounding rocks move and shake. The strength of an earthquake is measured on a scale based on the amount of energy released. Small earthquakes may just feel like a gentle trembling, but large powerful ones can cause immense damage to buildings and infrastructure and even trigger tsunamis. Earthquakes commonly occur at the boundaries where the Earth’s tectonic plates meet and along fault lines where old quakes have happened before. Studying them helps prepare for potential disasters.

List of Earthquakes in India

Earthquake	Year
Gujarat Earthquake	2001
Bihar Earthquake	1934
Maharashtra Earthquake	1993
Assam Earthquake	1950
Uttarkashi Earthquake	1991
Jabalpur Earthquake	1997
Sikkim Earthquake	2011
Indian Ocean Earthquake	2004
Kashmir Earthquake	2005
Andaman & Nicobar Earthquake	1941
Kinnaur Earthquake	1975
Koynanagar Earthquake	1967
Kangra Earthquake	1905
Anjar Earthquake	1956
Chamoli Earthquake	1999

1. Gujarat Earthquake (2001): An earthquake with a magnitude of 7.7 struck Gujarat, India on January 26, 2001, at 8:40 am, lasting for approximately two minutes. It caused widespread destruction in villages and towns, particularly in Bhuj, near the epicenter. The disaster claimed over 20,000 lives and partially damaged the famous Swaminarayan temple in Bhuj.
2. Bihar Earthquake (1934) or Bihar-Nepal Earthquake: The Bihar Earthquake, occurring on January 15, 1934, with a magnitude of 8.1, was one of India’s most devastating earthquakes. It affected northern Bihar and parts of Nepal, causing over 30,000 casualties. The worst-hit areas included Munger, Purnea, Champaran, and Muzaffarpur in Bihar, along with Kathmandu, Patan, and Bhaktapur in Nepal.
3. Maharashtra Earthquake (1993): Also known as the Latur earthquake, it struck Maharashtra on September 30, 1993, at 3:56 am, with a magnitude of 6.4. The epicenter was in Killari village, Latur district. Claiming over 20,000 lives, it severely affected Latur and Osmanabad, destroying numerous villages and prompting the establishment of the National Disaster Management Authority (NDMA).
4. Assam Earthquake (1950): The Assam Earthquake, occurring on August 15, 1950, with a magnitude of 8.6, severely affected Assam and Tibet. It claimed around 5,000 lives, with 1,500 casualties in Assam alone, and caused significant damage to both regions.
5. Uttarkashi Earthquake (1991): Also known as the Garhwal earthquake, it struck Uttarkashi, Tehri, and Chamoli districts in Uttarakhand on October 20, 1991, at 2:53 am, with a magnitude of 6.1. The quake affected around 307,000 people, resulting in 768 deaths and over 5,000 injuries, with vibrations felt up to New Delhi.
6. Jabalpur Earthquake (1997): Occurring on May 22, 1997, at 4:21 am, in Jabalpur district, Madhya Pradesh, this earthquake caused over 30 deaths and extensive damage to districts like Jabalpur, Seoni, Chhindwara, and Mandal, including destruction of villages and houses.
7. Sikkim Earthquake (2011): Also known as the 2011 Himalayan earthquake, it struck Sikkim and Nepal on September 18, 2011, at 6:10 pm, with a magnitude of 6.9. Claiming around 110 lives, it affected northeastern India, Bhutan, Nepal, southern Tibet, and Bangladesh.
8. Indian Ocean Earthquake (2004): The Indian Ocean earthquake, occurring on December 26, 2004, with a magnitude of 9.1-9.3, generated devastating tsunamis affecting countries adjacent to the Indian Ocean, resulting in over 200,000 deaths.
9. Kashmir Earthquake (2005): Striking on October 8, 2005, with a magnitude of 7.6, it caused over 80,000 casualties, displacing around 3 million people, with significant impacts in Muzaffarabad, Pakistan-administered Kashmir.
10. Andaman & Nicobar Earthquake (1941): The 1941 Andaman earthquake occurred on June 26, 1941, with a magnitude of 8.1, generating a tsunami affecting the Andaman Islands and neighbouring countries, causing around 8,000 deaths.
11. Kinnaur Earthquake (1975): This earthquake, occurring on January 19, 1975, with a magnitude of 6.8, caused severe destruction in Himachal Pradesh, particularly in the Kinnaur district, resulting in around 50 casualties.
12. Koynanagar Earthquake (1967): Striking on December 11, 1967, close to Koyna Dam in southwestern India, it resulted in around 200 deaths and extensive damage to villages and houses.
13. Kangra Earthquake (1905): The Kangra earthquake occurred on April 4, 1905, with a magnitude of 7.8, causing around 20,000 casualties and significant damage to buildings and historical structures in Himachal Pradesh.
14. Anjar Earthquake (1956): Striking on July 21, 1956, in Kutch district, Gujarat, with a magnitude of 6.1, it resulted in around 250 deaths and destruction of villages and houses.
15. Chamoli Earthquake (1999): Occurring on March 29, 1999, in Uttarakhand’s Chamoli district, with a magnitude of 6.8, it caused over 100 deaths and extensive damage to houses and villages in multiple districts.

Earthquake Zones in India

India is highly vulnerable to earthquakes due to its location at the boundary of the Indian and Eurasian tectonic plates. The country is divided into four major seismic zones based on scientific inputs relating to seismicity, earthquakes that occurred in the past, and soil conditions.

Zone V: This is the highest-risk seismic zone, where major earthquakes measuring 8.0 or more on the Richter scale can occur. Parts of Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Rann of Kutch in Gujarat, and the Andaman and Nicobar Islands fall under this zone.

Zone IV: This is a high-risk seismic zone where earthquakes of magnitude 7.0 to 8.0 can occur. Major cities like Delhi, Shillong, Leh, and parts of Jammu and Kashmir, Himachal Pradesh, and Uttarakhand fall in this zone.

Zone III: This is a moderate-risk seismic zone that can experience earthquakes of magnitude 6.0 to 7.0. Cities like Guwahati, Srinagar, Mumbai, Bangalore, Gandhinagar, and parts of Uttar Pradesh, Rajasthan, and Madhya Pradesh lie in this zone.

Zone II: This is a low-risk seismic zone that can experience earthquakes of magnitude 5.0 to 6.0. Major parts of Peninsular India like the Deccan Plateau and other stable continental regions fall under this zone.

The Bureau of Indian Standards has outlined specific construction guidelines for buildings and infrastructure in these seismic zones to minimize the risk of damage during earthquakes. Regular monitoring, disaster preparedness, and adherence to construction norms are crucial in mitigating the impact of earthquakes in these zones.

Consequences of Earthquakes

Here are the major consequences of earthquakes:

1. Loss of life and injuries:

Earthquakes can cause immense loss of life and injuries, especially in areas with high population density and poor building construction standards. Collapsing structures, falling debris, and fires are the leading causes of casualties.

2. Damage to infrastructure:

Earthquakes can severely damage buildings, bridges, roads, power lines, and other critical infrastructure. This disrupts essential services like water supply, electricity, transportation, and communication networks.

3. Economic losses:

The destruction caused by earthquakes can result in massive economic losses, including damage to residential and commercial properties, businesses, and industries. Rebuilding efforts can strain a region’s or country’s resources.

4. Homelessness:

Earthquakes can leave thousands or even millions of people homeless, either due to the destruction of their homes or the need to evacuate unsafe areas.

5. Environmental impacts:

Earthquakes can trigger landslides, soil liquefaction, and tsunamis (if they occur in the ocean), leading to environmental disasters. They can also cause fires, release of hazardous materials, and damage to natural habitats.

6. Psychological trauma:

Survivors of earthquakes can experience significant psychological trauma, including post-traumatic stress disorder (PTSD), anxiety, and depression, especially if they have witnessed loss of life or experienced the event firsthand.

7. Disruption of essential services:

Earthquakes can disrupt essential services like healthcare facilities, schools, and emergency services, making it difficult to provide aid and support to affected communities.

8. Secondary disasters:

Earthquakes can trigger secondary disasters, such as fires, dam failures, and the release of hazardous materials, compounding the overall impact and making rescue and recovery efforts more challenging.

Proper disaster preparedness, earthquake-resistant construction practices, and effective emergency response plans are crucial in mitigating the consequences of earthquakes and protecting lives and property.

Conclusion

Earthquakes are a natural phenomenon that can have devastating consequences, including loss of life, injuries, damage to infrastructure, economic losses, homelessness, environmental impacts, psychological trauma, and disruption of essential services. While some regions are more prone to earthquakes than others, it is crucial for all areas to prioritize disaster preparedness, implement earthquake-resistant construction practices, and have effective emergency response plans in place to mitigate the impact of these seismic events and protect lives and property.

Earthquakes in India-FAQs

What causes earthquakes?

Earthquakes are primarily caused by the movement of tectonic plates and the release of built-up energy along fault lines or zones of weakness in the Earth’s crust. Volcanic activity can also trigger earthquakes due to the movement of magma and the release of gases.

How are earthquake zones in India determined?

India is divided into four major seismic zones (V, IV, III, and II) based on scientific inputs relating to seismicity, past earthquakes, and soil conditions. These zones range from the highest-risk Zone V to the lowest-risk Zone II.

What are the consequences of a major earthquake?

Major consequences of a powerful earthquake can include loss of life and injuries, damage to infrastructure, economic losses, homelessness, environmental impacts, psychological trauma, disruption of essential services, and secondary disasters like fires and dam failures.

How can the impacts of earthquakes be mitigated?

The impacts of earthquakes can be mitigated through proper disaster preparedness, earthquake-resistant construction practices, regular monitoring and early warning systems, and effective emergency response plans that prioritize search and rescue, medical aid, and post-disaster recovery efforts.

Why is adherence to construction norms important in earthquake-prone areas?

Adherence to construction norms and guidelines specific to each seismic zone is crucial in earthquake-prone areas. These norms ensure that buildings and infrastructure are designed and constructed to withstand the potential shaking and stresses of an earthquake, reducing the risk of collapse and minimizing damage.