Delhi Residents Report A Loud "Boom" During Earthquake: What Was It?

A strong earthquake of magnitude 4.0 hit Delhi this morning and the tremors were felt in several adjoining areas of the national capital. According to the National Centre of Seismology, the quake hit at a depth of about 5 km. While there have been no casualties or injuries, residents reported a loud sound for a few seconds when the earthquake hit Delhi.

What was the loud sound?

The loud grumbling sounds during the tremors usually occur during a shallow-focus earthquake. According to the US Geological Survey (USGS), high-frequency vibrations from shallow earthquakes generate a booming sound as the ground vibrates and creates a short-period seismic wave motion that reaches the air and becomes sound waves. The shallower the epicentre, the more energy and sound can be produced.

Sometimes earthquakes can create booming sounds even when no vibrations are felt.

Also Read | Video Shows Moment 4.0 Magnitude Earthquake Hit Delhi-NCR

Why Delhi is prone to earthquakes

Delhi is located in the Seismic Zone IV which has fairly high seismicity, according to the Delhi Disaster Management Authority. In this zone, 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.

Seismicity in North India, including the Himalayas, is due to the collision of the Indian plate with the Eurasian plate. These colliding plates flex, and store energy like a spring, and when the plate's margin finally slips to release energy, an earthquake results.

Generally, shallow earthquakes, originating five or 10 kilometres below the surface, tend to cause more damage than those originating deep below the surface. The Dhuala Kuan area - the epicentre of today's quake - has been experiencing smaller, low-magnitude earthquakes once every two to three years. It had recorded an earthquake of 3.3 magnitude in 2015.

Residents recount earthquake tremors

The earthquake tremors woke the national capital up on Monday morning, with residents describing the moment as "one of the most insane earthquakes". Several videos also showed the moment the earthquake hit the national capital. CCTV footage from the terrace camera of a house in Delhi showed tank pipes and wires moving with heavy intensity.

A passenger waiting for his train at the New Delhi Railway station described the tremors as a "bridge collapse". "I was in the waiting lounge. All rushed out from there. It felt as if any bridge or something had collapsed," he said.

Another resident said, "Tremors were so strong. Felt like a train was moving nearby. Everything was shaking. I have never felt like this ever before. The entire building was shaking."

Shortly after the quake, the Delhi police urged citizens to call the emergency 112 helpline for emergencies. "We hope you all are safe, Delhi," they wrote on X.