Earthquakes have become so frequent in India, here is why!
India is a seismically active country due to its location on the boundary of two tectonic plates, the Indian Plate and the Eurasian Plate. The interaction of these plates creates various types of earthquakes in India, which can differ in their intensity, duration, and effects. In this article, we will discuss what causes an earthquake, what are the types of earthquakes and major earthquake zones in India.
What causes an earthquake?
An earthquake is caused by the sudden release of energy that has built up within the Earth’s crust. This energy is released in the form of seismic waves, which can cause the ground to shake and vibrate.
There are several reasons why earthquakes happen, but tectonic plate movement is the most frequent one. The Earth’s crust is made up of a number of large plates that move slowly over time. When these plates move, they can create stress within the Earth’s crust. This stress can build up over time until it is released suddenly, causing an earthquake.
Other causes of earthquakes include volcanic activity, which can cause earthquakes as magma moves beneath the Earth’s surface, and human activities such as mining, drilling, and the construction of large dams, which can also cause seismic activity. However, tectonic activity is the main cause of the great majority of earthquakes.
Types of Earthquakes
There are several types of earthquakes, but they can be broadly categorized into five main types based on their origin and the way they produce seismic waves:
Tectonic Earthquakes:
Tectonic earthquakes are the most common type of earthquakes in India. They occur when two tectonic plates move past each other or collide, causing a sudden release of energy that creates seismic waves. These earthquakes can occur at shallow or deep depths and can range in magnitude from small tremors to large earthquakes.
One of the most well-known tectonic earthquakes in India is the 2001 Bhuj earthquake, which had a magnitude of 7.7 and caused significant damage to buildings and infrastructure in the state of Gujarat. Another example is the 2015 Nepal earthquake, which had a magnitude of 7.8 and affected many parts of India, including Bihar, Uttar Pradesh, and West Bengal.
Intraplate Earthquakes:
Intraplate earthquakes occur within a tectonic plate, away from plate boundaries. They are less common than tectonic earthquakes but can still be significant. Intraplate earthquakes in India are thought to occur due to the stresses caused by the interaction of the Indian Plate with the surrounding plates.
One of the most significant intraplate earthquakes in India occurred in 1993 in the Latur region of Maharashtra, which had a magnitude of 6.2 and caused widespread damage and loss of life.
Induced Earthquakes:
Induced earthquakes are earthquakes that are caused or triggered by human activity. These earthquakes can occur due to activities such as mining, oil and gas extraction, and the construction of large dams. In India, induced earthquakes are becoming more common due to the increasing development of infrastructure and industrial activities.
One example of an induced earthquake in India occurred in 2017 in the state of Assam, where a 6.4 magnitude earthquake was linked to the construction of a hydroelectric dam.
Volcanic Earthquakes:
Volcanic earthquakes occur in areas with active volcanoes or volcanic systems. They are caused by the movement of magma and the release of gases within the earth’s crust. While India does not have any active volcanoes, there are several areas with dormant volcanoes or volcanic systems, such as the Barren Island volcano in the Andaman Sea.
Reservoir-Induced Earthquakes:
Reservoir-induced earthquakes occur due to the weight of water in large reservoirs, which can cause stresses on the earth’s crust and trigger earthquakes. India has many large dams and reservoirs, and reservoir-induced earthquakes are becoming more common due to the increasing construction of such infrastructure.
One example of a reservoir-induced earthquake in India occurred in 1967 in the Koyna region of Maharashtra, where a 6.3 magnitude earthquake was linked to the construction of a large dam.
Major Earthquake Zones
India is a seismically active country with five major earthquake zones, each with unique characteristics and seismic risks. The zones are based on the intensity and frequency of earthquakes, as well as the geology and tectonic activity of the region.
Zone V:
The most vulnerable regions to earthquakes of magnitude MSK IX or higher fall under Zone 5. According to the IS code, Zone 5 has a zone factor of 0.36. This element is used by structural designers to create earthquake-resistant constructions in Zone 5. Effective (zero period) level earthquakes are likely to occur in this zone, according to the zone factor of 0.36 (the greatest horizontal acceleration that a structure can experience).
The Very High Damage Risk Zone is the name given to it. This area includes the Himalayan regions of the Western and Central Himalayas, Kashmir, North and Middle Bihar, North-East India, the Rann of Kutch, and the Andaman and Nicobar group of islands. Typically, basaltic or trap rock-containing locations are more prone to earthquakes.
Zone IV:
The High Damage Risk Zone encompasses places susceptible to MSK VIII and is known as such. Zone 4 is given a zone factor of 0.24 per the IS code. Jammu and Kashmir, Ladakh, Himachal Pradesh, Uttarakhand, Sikkim, and parts of the Indo-Gangetic plains are all included in Zone 4 of India.
(North Punjab, Chandigarh, Western Uttar Pradesh, Terai, a sizable piece of Bihar, North Bengal, and the Sundarbans). It also includes the nation’s capital, Delhi. Zone 4 in Maharashtra includes the Patan neighbourhood (Koynanagar).
Zone III:
This area is a Moderate Damage Risk Zone that is subject to MSK VII. For Zone 3, the IS code assigns a zone factor of 0.16. There are a number of megacities in this region, including Chennai, Mumbai, Kolkata, and Bhubaneshwar.
Zone II:
This area is categorised as a Low Damage Risk Zone because it is susceptible to MSK VI or lower. Zone 2 is given a zone factor of 0.10 under the IS code. It is the area where earthquakes are least likely to occur. This region includes cities like Bangalore, the Coromandel Coast, and Tiruchirappalli.
Zone I:
No part of India is classified as Zone 1 because the current system of dividing the country into seismic hazard zones does not employ Zone 1.
Why earthquakes are so frequent in India?
Because some areas of India and Nepal are situated on the boundary (fault zones) of two enormous tectonic plates, India frequently experiences earthquakes in its northern and north-eastern regions. The Himalayas were created when the Indian plate shifted towards the Nepalese plate. Both countries are now more susceptible to earthquakes as a result of the two plates colliding.
The Sohna fault line, the Mathura fault line, and the Delhi-Moradabad fault line are all active seismic fault lines that cross through Delhi. Gurgaon, which is situated on no fewer than seven fault lines, is the most dangerous area of the Delhi-National Capital Region.
The Effects of Earthquakes in India?
The effects of earthquakes in India can be devastating, resulting in loss of life, damage to property, and disruption of essential services. Here are some of the impacts of earthquakes in India:
Loss of Life: Earthquakes can result in the loss of life, particularly in densely populated areas with poor building standards and inadequate infrastructure. The 2001 Gujarat earthquake, which had a magnitude of 7.7, resulted in the deaths of more than 20,000 people.
Damage to Infrastructure: Earthquakes can cause extensive damage to buildings, roads, bridges, and other critical infrastructure. The 2015 Nepal earthquake, which had a magnitude of 7.8, caused significant damage to infrastructure in India’s northern states.
Disruption of Essential Services: Earthquakes can disrupt essential services such as power, water, and communications. This can lead to significant disruptions in daily life, particularly in areas that are already vulnerable.
Economic Losses: Earthquakes can result in significant economic losses due to damage to property and infrastructure, loss of productivity, and increased costs associated with rebuilding and recovery efforts.
Psychological Effects: The mental health of those who encounter earthquakes might be seriously impacted. Particularly among those who have lost loved ones or had significant property loss, they have the potential to cause post-traumatic stress disorder (PTSD), anxiety, and depression.
Safety Measures to Follow During Earthquakes
Earthquakes can strike without warning, making it essential to be prepared and know what to do in the event of an earthquake. Here are some safety measures to follow during earthquakes:
Drop, Cover, and Hold On: When you feel an earthquake, drop to the ground, take cover under a sturdy piece of furniture, and hold on until the shaking stops. Stay away from windows, mirrors, and anything that could fall and cause injury.
Stay Indoors: Stay indoors until the shaking stops and it is safe to exit the building. If you are in a high-rise building, don’t stay near windows and outside walls, and avoid using elevators.
Evacuate if Necessary: If you are in a building that is at risk of collapsing or if authorities advise you to evacuate, do so immediately. Use stairs instead of elevators, and stay away from damaged areas.
Check for Injuries: Check for injuries on both you and other people, and get medical help if required. If you have had first aid training, administer it.
Turn Off Utilities: Turn off gas, water, and electricity if you suspect a leak or damage. You should immediately leave the area if you smell gas and contact the gas company.
Stay Informed: Stay tuned to local news and follow the instructions of authorities. Do not share any unverified information.
Have an Emergency Kit: Keep an emergency kit ready that includes food, water, first aid supplies, and a flashlight. Make sure you have a plan in place for your family and know how to contact each other in case of separation.
Final words
Although earthquakes are unpredictable, there is a chance that one of the two seismic zones, V and IV, which cover the entire Himalaya and Delhi-NCR, would experience a major to huge earthquake with a magnitude of 6 or greater.
Effective earthquake preparedness is the only way to reduce the number of lives and property lost. This has been demonstrated by nations like Japan, where earthquakes are a routine occurrence but the losses are minimal. Success depends on people’s involvement, cooperation, and awareness.
