An earthquake is caused by a fault, which is a sharp rupture in the crustal rocks. When lithospheric plates shift, the Earth's surface vibrates. An earthquake is the abrupt release of energy in the Earth's crust that causes seismic waves. The location of energy buildup is recognized by deformed rocks induced by tension or compression. In India, the whole region comprising fourteen states centered in the western and central Himalayas, northeast, and sections of the Indo-Gangetic basin is particularly prone to earthquakes. This article will explain to you the Earthquakes in India which will be helpful in Geography preparation for the UPSC Civil service exam.

Earthquake - Concept

• In simple terms, an earthquake is the ground shaking. It's a natural occurrence.
• It occurs as a result of the release of energy, which causes waves to propagate in all directions.
• Seismic waves are vibrations that are created by earthquakes as they move through the Earth and are recorded on seismographs.
• The hypocenter is the point under the earth's surface where the earthquake begins, while the epicenter is the position directly above it on the earth's surface.
• Seismic waves are waves produced by an earthquake and are recorded by a seismograph.
• The Richter Scale measures the magnitude (energy released) of an earthquake, whereas the Mercalli Scale measures the severity (damage inflicted).
• The rocks along the route of P waves are compressed/expanded in the direction of propagation during an earthquake, affecting their volume rather than their form. S waves affect the form rather than the volume.
• Due to the suddenness, earthquakes are by far the most unexpected and extremely damaging of all-natural catastrophes.
• Earthquakes of tectonic origin have shown to be the most catastrophic, with a far larger region of an effect than other sources.

Earthquakes in India

• Earthquakes of moderate magnitude occur on a daily basis. Strong tremors that cause widespread devastation, on the other hand, are less common.
• Earthquakes are more common around plate borders, particularly along convergent boundaries.
• The region where the Indian Plate and the Eurasian Plate collide in India is more earthquake-prone. Take, for example, the Himalayan region.
• The peninsular region of India is regarded as a stable region. However, some earthquakes are occasionally felt along the margins of minor plates.
• Earthquakes in peninsular regions include the 1967 Koyna earthquake and the 1993 Latur earthquake.
• India has been categorized into four seismic zones by Indian seismologists: Zone II, Zone III, Zone IV, and Zone V.
• It can be seen that the whole Himalayan area, as well as the states of North-East India, Western and Northern Punjab, Haryana, Uttar Pradesh, Delhi, and parts of Gujarat, are classified as zone V and IV, respectively.
• The northern lowlands and western coastal areas remain in the moderate danger zone, while a substantial portion of the peninsular region is in the low-risk zone.

Earthquakes in India - Zone Classification

• Modified Mercalli (MM) intensity, which assesses the effect of earthquakes, is used to separate the zones.
• However, after the Killari earthquake in Maharashtra in 1993, the seismic zoning map was revised, with the low danger zone, or Seismic Zone I, being amalgamated with Seismic Zone II.
• As a result, Zone I is not included in the mapping.
• Zone II: It is classified as a low-intensity zone.
  • It covers 40.93 percent of the country's surface.
  • It includes the peninsular area as well as the Karnataka Plateau.
• Zone III: This is a moderately intense zone.
  • It spans 30.79 percent of the country's surface.
  • Kerala, Goa, and the Lakshadweep Islands, as well as parts of Punjab, Rajasthan, Madhya Pradesh, Bihar, Jharkhand, Chhattisgarh, Maharashtra, Odisha, Andhra Pradesh, Tamil Nadu, and Karnataka, make up the state.
• Zone IV: It is classified as a high-intensity zone.
  • It covers 17.49% of the country's surface area.
  • It includes the remaining sections of Jammu and Kashmir, Himachal Pradesh, Delhi's National Capital Territory (NCT), Sikkim, Uttar Pradesh's northern parts, Bihar, West Bengal, parts of Gujarat, Maharashtra's west coast, and Rajasthan.
• Zone V: It is classified as a zone of extreme severity.
  • It covers 10.79 percent of the country's surface area.
  • It includes sections of Jammu and Kashmir, Himachal Pradesh, Uttarakhand, the Rann of Kutch in Gujarat, a portion of North Bihar, and the Andaman and Nicobar Islands.

Earthquakes in India - Consequences

Avalanches and Landslides

• Tremors, particularly in mountainous places, can result in slope instability and collapse, resulting in debris falling down the slope and creating landslides.
• Avalanches caused by earthquakes may cause massive amounts of ice to cascade down snow-covered peaks.
• As an example, Several avalanches occurred on and around Mount Everest as a result of the 2015 Nepal earthquake.
• The 2011 earthquake in Sikkim resulted in landslides and significant damage to lives and property, particularly at the Singik and Upper Teesta hydroelectric facilities.

Floods

• The earthquake has the potential to produce dam and reservoir failures, as well as flash floods.
• Landslides and avalanches might obstruct the river's flow, causing flooding.
• Due to the accumulation of massive debris, the Assam earthquake of 1950 created a barrier in the Dihang River, creating flash floods in the upstream part.

Tsunami

• Tsunamis are waves that occur when an ocean basin is disrupted and a large volume of water is displaced.
• Tsunamis are caused by earthquake seismic waves displacing the seafloor and generating high sea waves.
• An earthquake off the coast of Sumatra triggered the Indian Ocean Tsunami on December 26, 2004.
• It occurred as a result of the Indian plate subducting beneath the Burmese plate.
• It killed over 2.4 lakh people in the Indian Ocean region and its surrounding nations.
• The huge Tohoku earthquake in Japan in 2011 resulted in Tsunami waves of ten meters, which were generated by an underwater earthquake of magnitude nine.
• The emergency generators cooling the reactors were destroyed, resulting in a nuclear meltdown and the radioactive fallout from Fukushima Daiichi becoming a global issue.

Loss of human life and property

• The deformation of the ground surface caused by the vertical and horizontal movement of the earth's crust causes massive damage and devastation to human settlements and structures.
• An example: A case study of the 2015 Nepal earthquake's urban devastation.
• This earthquake had a magnitude of 7.8 and was 8.2 kilometers deep. Because of uncontrolled urban development, poorly engineered buildings, and unscientifically designed structures, the Nepal earthquake claimed many lives.
• Kathmandu's urban districts were severely damaged, resulting in the deaths of 8,000 people and a ten-billion-dollar economic loss.

Earthquake Management in India

• The organization and administration of resources and duties for dealing with all humanitarian elements of calamities are referred to as earthquake management.
• The goal is to lessen the dangers' negative impact. Pre-earthquake risk reduction through post-earthquake recovery is all part of earthquake management.
• Recognize the danger - Because certain regions are more prone to earthquakes than others, recognizing the risk is the first step.
• Early warning system/earthquake monitoring system– It is still impossible to make an exact prediction regarding the occurrence of an earthquake in a certain location.
• Seismologists are increasingly focusing their efforts on earthquake prediction.
• It will aid in mitigating the effects of impending calamities.
• For instance, Japan has an early warning system for earthquakes that employs electronic signals that travel quicker than seismic waves.
• Structural Solution – During previous earthquakes, almost 95 percent of people died as a result of structures that were not earthquake resistant collapsing.
• However, the cost of constructing quake-resistant structures is higher than that of typical structures.
• As a result, finding a cost-effective solution for a country like India remains difficult.
• Seismic strengthening may be accomplished by prioritizing structures, and in order to do so, an earthquake hazard map for various zones based on vulnerability is required.

Conclusion

The lithosphere is the source of all-natural earthquakes. Seismic wave investigations provide a complete image of the inner layers. Simply described, an earthquake is the shaking of the earth's crust. It is created by the discharge of energy, which causes waves to propagate in all directions. India is a country where the area where the Indian Plate and the Eurasian Plate clash is more prone to earthquakes.

FAQs

MCQs

1. Which of the following tectonic plates is responsible for most earthquakes in Northern India?

A) African Plate
B) Indian Plate
C) Pacific Plate
D) Australian Plate

2. Which region in India is known as the most seismically active?

A) Deccan Plateau
B) Western Ghats
C) Himalayan Belt
D) Thar Desert

3. What does the Richter scale measure?

A) The depth of the earthquake
B) The total energy released by the earthquake
C) The amplitude of seismic waves
D) The area affected by the earthquake

4. What is an essential measure to mitigate earthquake impact?

A) Building taller structures
B) Enforcing building codes
C) Planting more trees
D) Widening roads

5. Which scale is more effective in measuring the energy released by larger earthquakes?

A) Richter scale
B) Celsius scale
C) Moment magnitude scale (Mw)
D) Decibel scale

GS Mains Questions and Model Answers

Q1: Analyze the reasons why the Himalayan region is highly susceptible to earthquakes. What challenges does this pose for disaster management in the area?

Answer: The Himalayan region is highly susceptible to earthquakes due to the ongoing tectonic collision between the Indian Plate and the Eurasian Plate. This convergence results in significant geological stress along fault lines, making the region prone to seismic activity. The high population density, difficult terrain, and limited infrastructure pose substantial challenges for disaster management. Effective measures include developing earthquake-resistant infrastructure, enhancing early warning systems, and promoting community preparedness. Addressing these challenges requires coordinated efforts involving governments, local communities, and international experts to minimize potential losses and ensure rapid response during seismic events.

Q2: Discuss the differences between the Richter scale and the moment magnitude scale (Mw). Why is the moment magnitude scale preferred for measuring large-scale earthquakes?

Answer: The Richter scale and the moment magnitude scale (Mw) both measure earthquake magnitude, but they differ in approach. The Richter scale measures the amplitude of seismic waves, providing a logarithmic value for earthquake magnitude. It is effective for smaller to moderate earthquakes but becomes less accurate for larger events. The moment magnitude scale (Mw), on the other hand, measures the total energy released by an earthquake, offering a more comprehensive and consistent assessment across all magnitudes. This scale is preferred for large-scale earthquakes as it provides a more accurate depiction of the seismic event's true size and energy, which is critical for understanding and preparing for its potential impact.

Q3: Evaluate the effectiveness of current earthquake mitigation measures in India. What improvements can be made to strengthen disaster preparedness?

Answer: Current earthquake mitigation measures in India include enforcing building codes, conducting public awareness campaigns, and deploying early warning systems. However, challenges such as unregulated construction, inadequate enforcement of safety standards, and limited access to technology hinder their effectiveness. Improvements can be made by stricter enforcement of building codes, retrofitting older structures, expanding the reach of early warning systems, and incorporating advanced technology for real-time monitoring. Enhanced community training and regular drills can also bolster disaster preparedness, ensuring that people know how to respond during an earthquake. Collaborative efforts between government agencies, researchers, and local communities are essential for strengthening these measures and reducing earthquake-related risks.

Previous Year Questions on Earthquakes in India

1. UPSC CSE Prelims 2021:

Question: Which of the following regions in India is most prone to seismic activity?

A) Deccan Plateau
B) Western Ghats
C) Northeast India
D) Rajasthan Desert

Answer: (C)

Explanation: Northeast India is highly prone to seismic activity due to the complex tectonic interactions between the Indian Plate and the Eurasian Plate. This region has experienced some of the most significant earthquakes in Indian history.

2. UPSC CSE Mains 2020 (GS Paper 1):

Question: "What are the major causes of earthquakes in India? Discuss the measures taken by the government to mitigate the impact of earthquakes."

Answer: The major causes of earthquakes in India include tectonic activity due to the movement of the Indian Plate against the Eurasian Plate, especially in the Himalayan region. Other causes include seismic activity along fault lines in the Northeast and certain regions of Western and Central India. The government has implemented several measures to mitigate the impact of earthquakes, such as enforcing seismic-resistant building codes, conducting awareness programs, and deploying early warning systems. The National Disaster Management Authority (NDMA) plays a key role in formulating policies and coordinating disaster response. Despite these efforts, continuous improvement in infrastructure, technology, and public education is needed to enhance resilience against future earthquakes.