NDTV explanator: why Delhi faces a high risk of earthquakes

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A strong earthquake hit Delhi early this morning and the tremors were felt across north India. Residents rushed out of their houses as per the protocol, claiming they had never felt an earthquake as strong in the past. The quake was of 4.0 magnitude and it hit at a depth of about 5 km, according to an update from the National Centre of Seismology, the centre's nodal agency that tracks earthquake activity.


The epicentre was in Delhi, near the Durgabhai Deshmukh College of Special Education in Dhaula Kuan, suggest reports. It sparked panic and forced the residents of high-rise buildings in the neighbouring cities of Noida and Ghaziabad to evacuate as well.




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Prime Minister Narendra Modi soon appealed to the residents to stay calm and follow the safety protocols. Stating the authorities are keeping a close watch, he said online that the residents must stay alert for possible aftershocks.


Read: "Never Felt Like This": Delhi Residents On Strong Earthquake Tremors


Several residents claimed they were panicked seeing the buildings shaking while a passenger at a railway station said he felt that a train was running underground.


Such earthquakes are not unusual in Delhi due to its geographic location. The city has been rocked by frequent such tremors in the past - in 2020, at least three earthquakes above 3.0 magnitude hit the national capital, followed by a dozen aftershocks.


Delhi is located in the Seismic Zone 4 which has a higher risk of earthquakes, according to the Delhi Disaster Management Authority. This zone has a fairly high seismicity where earthquakes generally occur in the range of 5-6 magnitude, and even 7-8 occasionally. The zoning, however, is a continuous process that keeps changing.

Read: 

"Stay Alert For Possible Aftershocks": PM Modi On Delhi Earthquake


Since 1720, the city has been rocked by at least five earthquakes above 5.5 magnitude on the Richter scale, reports suggest.


The earth's crust - the thin outermost layer - is made of large and solid slabs of rock known as tectonic plates. There are about seven major and minor such plates. These plates move very slowly, causing deformations that lead to earthquakes.


In North India, including the Himalayas, the collision of the Indian tectonic plate with the Eurasian plate contributes to seismicity or the frequency of earthquakes. These plates store energy like a spring and when they slip above one another, it releases the energy and results in an earthquake.


"Seismicity around Delhi appears to be associated with a major geological structure, which is known as the Delhi-Hardwar Ridge. It coincides with the extension of the Aravali Mountain belt beneath the alluvial plains of the Ganga basin to the northeast of Delhi towards the Himalayan mountain," according to the DDMA website.


Besides being in Seismic Zone IV, a SWOT analysis by the National Disaster Management Authority (NDMA) has found that the national capital also faces threats due to the high number of non-earthquake resilient buildings, high population density, unplanned and unsafe structures and co