Delhi’s Seismic Wake-Up Call: Mild Tremor Highlights Earthquake Vulnerability

(Source – Indian Express, Section – Explained – Page No. – 16)

Topic: GS1 – Geography

Context

A magnitude 4 earthquake originated in Delhi, marking the strongest local tremor in five years and highlighting the city’s seismic vulnerability.

Analysis of the news:

What is an Earthquake?

An earthquake is the shaking of the Earth’s crust caused by a sudden release of energy. This release of energy occurs along a fault, which is a break in the Earth’s crustal rocks. How do earthquakes occur? Earthquakes are caused by the movement of tectonic plates. When two tectonic plates slide past each other, the jagged edges can get caught, and when they release, the energy is released as vibrations. Earthquakes can also be caused by the injection or withdrawal of magma, or explosions of chemical or nuclear devices.

Seismic Activity in Delhi

• Delhi experiences frequent tremors, mainly from distant earthquakes.

• However, the recent magnitude 4 earthquake originated within Delhi, near Dhaula Kuan, marking the strongest local tremor in five years.

• While not destructive, it highlights the city’s seismic vulnerability.

Delhi’s Earthquake Susceptibility

• Classified under Zone 4 in India’s earthquake hazard map, Delhi is prone to MSK-8 intensity quakes, which can cause significant infrastructure damage.

• The intensity of shaking varies based on local geology, making Delhi more susceptible despite moderate earthquake magnitudes.

Aravalli-Delhi Fold Belt and Seismicity

• Delhi lies within the Aravalli-Delhi Fold Belt, a geological zone stretching from Rajasthan to Haryana.

• This region, shaped by ancient geological processes, has residual fault lines that occasionally trigger mild earthquakes.

• Unlike the Himalayas, where active tectonic plate movements generate frequent quakes, Delhi’s seismic activity is sporadic and less intense.

Unusual Sound Phenomenon

• Some Delhi residents reported hearing an unusual sound during the quake.

• While earthquakes can produce sound waves, they are typically beyond human hearing.

• More likely, the noise resulted from buildings and structures vibrating, rather than the earthquake itself.

Low Probability of Major Earthquake

• Historical records mention strong earthquakes in Delhi in 1720 and 1803, but modern studies suggest they likely originated elsewhere.

• Delhi’s geological setup lacks the energy and stress conditions needed for large quakes.

• Although a severe earthquake from another region could impact Delhi, the likelihood of a major quake originating within the city remains low.

Conclusion

• Delhi’s recent earthquake, though mild, underscores its seismic vulnerability.

• Positioned in Zone 4, the city is prone to moderate tremors due to residual fault lines in the Aravalli-Delhi Fold Belt.

• While the likelihood of a major earthquake originating in Delhi is low, preparedness remains crucial due to the city’s dense population and infrastructure.

Is Delhi Ready for an Earthquake?

While Delhi’s earthquake preparedness has improved over the years, both authorities and residents need to remain vigilant and prepared. The February 17, 2025 earthquake was a reminder that even moderate earthquakes can cause significant concern, especially in densely populated urban areas. Given Delhi’s location in Seismic Zone IV, earthquakes will continue to be a concern. By staying informed, securing homes, and following safety protocols, residents can mitigate the risks and ensure their safety in the event of future seismic activity.

Practice Question: Delhi lies in a seismically active region, yet the likelihood of a major earthquake originating within the city is low. Discuss the geological factors influencing Delhi’s seismic activity and the measures needed to enhance earthquake preparedness in urban areas. (250 Words /15 marks)