An earthquake is caused by tremors due to the movement of the tectonic plates inside the earth.
Strong tremors were felt in several parts of north India including Delhi, Noida, and Gurugram on Tuesday night after a massive earthquake hit Afghanistan. The tremors were felt for several seconds. This was a massive earthquake in recent times. The 6.6 magnitude earthquake struck the Hindu Kush region in Afghanistan.
The earthquakes are frequent in India including Delhi-NCR for the past few months. But why are there frequent earthquakes in India and what causes an earthquake?
An earthquake is caused by tremors due to the movement of the tectonic plates inside the earth. These plates are deep down inside the uppermost layer of the earth called the crust. When two blocks of the earth’s surface move against each other, it causes an earthquake.
An earthquake originates from 'focus', a place inside Earth’s crust. The nearest place on the surface from a focus is called 'epicentre'. When energy is released at the focus, seismic waves travel outward from that point in all directions.
India's northern region has the Himalayas which are the newest mountains. The Indian plate moved towards the Nepalese plate, which led to the formation of the Himalayas.
The Himalayas lies between North India to Northeast India. India experiences frequent earthquakes in these regions because this part of India and Nepal are placed on the boundary (fault zones) of two massive tectonic plates. The collision of the two plates also made both countries vulnerable to earthquakes.
READ | Earthquake: Strong tremors rock Delhi NCR, several other parts of North India
According to the government of India, a total of nearly 59% of the land mass of India (covering all states of India) is prone to earthquakes of different intensities.
As per the seismic zoning map of the country, the total area is classified into four seismic zones. Zone V is seismically the most active region, while zone II is the least. Eight states and Union Territories are in zone-5 and are at risk of earthquakes of the highest intensity. The Delhi-NCR region is in zone IV.
Percentage of India’s total landmass area in Earthquake Seismic Zone:
Zone V: 11% (most active)
Zone IV: 18%
Zone III: 30%
Zone II: 41% (least active)
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 "DNA Explainer: Why Delhi, Noida, Gurugram and nearby areas witness earthquakes so frequently?")
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