Earthquake in Delhi: Why is Delhi NCR so prone to earthquakes?

Tremors once again jolted the national capital, the adjoining areas, and other parts of north India, forcing people out of their homes in panic. This marks the third time in the last month that tremors have hit Delhi-NCR. On October 15, the national capital experienced an earthquake of magnitude 3.1 on the Richter scale, with an epicentre located 9 kilometres east of Faridabad.

Two earthquakes of magnitude 4.6 and 6.2 hit Nepal on October 3, causing strong tremors in Delhi and NCR after 25 minutes. People in parts of Uttarakhand and Uttar Pradesh capital Lucknow, Hapur, and Amroha felt the quake, which lasted for nearly 40 seconds.

Delhi’s geographical location makes it prone to frequent earthquakes. The city lies in the Himalayan foothills, a region known for its seismic activity due to the movement of tectonic plates. Scientific studies have highlighted that the Indian plates are continuously driving towards the Eurasian plates at a rate of 5-6 cm per year.

Delhi-NCR is not located on a fault line. However, the Lutyens' area, where the Parliament is situated, is a high-hazard zone. Other vulnerable areas include the north campus of Delhi University, Janakpuri, Rohini, Karol Bagh, Paschim Vihar, Sarita Vihar, Gita Colony, and Shakarpur.

What causes frequent Earthquakes in Delhi-NCR 

Delhi-NCR is prone to earthquakes because of its proximity to the Himalayan tectonic plate boundary. The Indian and Eurasian plates collide at this boundary, which is responsible for the seismic activity in the region. The movement of these plates can cause stress to build up in the Earth's crust, which can eventually lead to earthquakes. This constant tectonic activity results in regular tremors, making the region an epicenter for recurring natural calamities like earthquakes.

Delhi is located near three active seismic fault lines: Sohna, Mathura, and Delhi-Moradabad. Experts say Gurugram is the riskiest area in Delhi-NCR as it is situated on seven fault lines. If these get active, a quake of high intensity is imminent. Seismologists say that since Delhi-NCR is close to the Himalayas, it feels the changes that take place in the tectonic plates. Any earthquake in the Himalayan belt affects Delhi-NCR.

Additionally, the proximity to the Himalayan tectonic plate boundary primarily associates the region's seismic risk. Here, the Indian plate collides with the Eurasian plate. This collision is responsible for the significant seismic activity in northern India, including Delhi and its neighboring areas.

Delhi itself does not sit on a major fault line, but its location near the Himalayas places it in a seismically active region. Therefore, the close proximity of Nepal, Uttarakhand, and the adjoining Himalayan region makes them vulnerable to a devastating earthquake with an intensity of more than 8.5 on the Richter Scale.

Delhi earthquake timeline

• 8 June - 21 Richter Scale - Delhi

• 3 June - 3.2 Richter Scale - Faridabad

• 1 June - 3 Richter Scale - Rohtak

• 1 June - 1.8 Richter Scale - Rohtak

• 29 May - 2.9 Richter Scale - Rohtak

• 29 May - 4.5 Richter Scale - Rohtak

• 22 May – 2.2 Richter Scale - Pitampura

• 15 May - 2.2 Richter Scale - New Delhi

• 10 May - 3.4 Richter Scale - Delhi

• 06 May - 2.3 Richter Scale - Faridabad

• 03 May - 3.0 Richter Scale - Delhi

• 16 April - 2.0 Richter Scale - Delhi

• 13 April - 2.7 Richter Scale – Delhi

• 12 April - 3.5 Richter Scale – Delhi

India's Seismic Mapping 

The proximity of Delhi to the Himalayan region places it under seismic Zone IV, while the Himalayan regions themselves fall under seismic Zone V, implying the highest risk of damaging earthquakes.

"In India, eight states and Union Territories fall under Zone V, which is prone to the risk of the highest intensity earthquakes."

According to data from the Government of India, different intensities of earthquakes can affect around 59 per cent of the country's land mass. Approximately, zone V covers 11% of the country’s area, zone IV 18%, zone III 30%, and the remaining area falls into zone II.

Important cities in seismic zone V: Bhuj (Gujarat), Darbhanga (Bihar), Guwahati (Assam), Imphal (Manipur), Jorhat (Assam), Kohima (Nagaland), Mandi (Himachal Pradesh), PortBlair (Andaman and Nicobar), Sadiya (Assam), Tezpur (Assam). 

Parts of Uttarakhand, Haryana, Punjab, Uttar Pradesh, Bihar, West Bengal, Sikkim, Himachal Pradesh, Chandigarh, and New Delhi fall under Zone IV. 

Reasons

Here are the reasons why so many earthquakes occur in Delhi NCR throughout the year.

• Geological Factors: Delhi is located on the boundary of the Indian and Eurasian tectonic plates, which are constantly moving towards each other. This movement can cause stress to build up in the Earth’s crust, leading to earthquakes.
• Active Fault Lines: There are several active fault lines in and around Delhi NCR, including the Sohna fault line, the Mathura fault line, and the Delhi-Moradabad fault line. These fault lines can slip and generate earthquakes if they are triggered by tectonic activity.
• Soft Soil: Delhi NCR is built on soft soil, which can amplify the shaking caused by earthquakes. This can make earthquakes in the region more destructive.
• Location: The Himalayas, the youngest mountains in the world, were formed by the collision of the Indian and Eurasian tectonic plates. This collision zone is highly seismically active and is prone to frequent earthquakes.
• Impact of a Major Earthquake: A major earthquake in Delhi NCR could have a devastating impact on the city. The city is home to a large population and is densely built, which means that there is a high risk of loss of life and damage to infrastructure.

Do these earthquakes signal a major one?

So many mild earthquakes in Delhi since May have raised speculation about a big one, but scientists say these are not unusual. Scientists are unequivocal that there is no unusual seismic activity around Delhi.

“There is absolutely nothing happening in Delhi that can be called unusual or abnormal,” said Vineet Gehlot, former head of the National Centre for Seismology in Delhi. Also, the fact is that out of the 115 detectors installed in the country, 16 are in or around Delhi which is even more than the Himalayan region.

"We also record very low tremors and make them accessible to the public. Delhi-NCR, in terms of zones, falls in Zone IV, designated as 'severe.' “A big earthquake might still occur. No one can rule it out. But we cannot predict them. "So, saying that these small earthquakes are precursors to the big one is totally unscientific," Harsh Gupta, one of India's foremost experts on earthquakes and former director of NGRI, stated.

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