Powerful tremors felt in Delhi due to 'local effect', it wasn't plate tectonic earthquake: Details here

The 4.0 magnitude earthquake that shook New Delhi and surrounding regions on Monday (Feb 17) was caused by "in situ material heterogeneity", a senior expert said. While speaking to the news agency PTI, National Centre for Seismology Director OP Mishra said that the tremors were felt due to "local effects" as it was not a plate tectonic earthquake. 

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The epicentre was at Jheel Park in Dhaula Kuan, at a depth of 5 km, which is called shallow depth. According to Mishra, seismologically, it is not a new region as earthquakes have happened earlier as well in the same region. 

In 2007, the Dhaula Kuan region experienced a 4.6-magnitude earthquake. However, the impact was not as strongly felt as Monday's shaking, as it had taken place at a depth of 10 km. 

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"Earlier, there was a 4.6 magnitude earthquake in 6 km periphery, but it was deeper, with 10 km depth," Mishra said, further adding that after Monday's quake, "we can expect aftershock of around 1 or 1.2 magnitude". 

VIDEO | As Delhi-NCR was jolted by an early morning earthquake, National Centre for Seismology Director OP Mishra says, "The epicentre was at Jheel Park in Dhaula Kuan, it was a 4.0 magnitude earthquake. It was in the depth of 5 km, it is called shallow depth, hence people felt… pic.twitter.com/PbVsNMofGU

— Press Trust of India (@PTI_News) February 17, 2025

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How do earthquakes occur due to in situ material heterogeneity? 

Earthquakes due to in situ material heterogeneity refer to seismic activity caused by the inherent variability in the physical properties of the Earth's crust. Some of the physical properties include rock type and composition, pore fluid distribution, fracture networks, and mineralogy and texture. 

The material heterogeneities can lead to stress concentration, which means accumulation of stress in certain areas due to variations in rock properties, which eventually increase the likelihood of earthquakes. 

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Heterogeneities can also scatter seismic waves, affecting their propagation, potentially leading to complex earthquake behaviour, and they can also influence the development of fault zones, making them more prone to earthquake activity. 

Delhi is placed in seismic zone IV in the seismic zoning map of India, the second highest in the country.

(With inputs from agencies)