New Delhi:

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.

National Center for Seismology said the earthquake struck at a focal depth of five kilometres in Delhi-NCR on February 17, 2025
| Photo Credit: Special arrangement

Strong tremors were felt in the national capital and adjoining regions as an earthquake of 4.0 magnitude struck the region early on Monday (February 17, 2025). The National Center for Seismology said the earthquake struck at a focal depth of five kilometres at 5:36 am.

After Delhi, NCR, tremor felt in Bihar also at 4.0 magnitude. The National Center for Seismology said the earthquake struck at a depth of 10 kilometres at 8:02 am.

Shallow earthquakes, originating five or 10 kilometres below the surface, tend to cause more damage than those originating deep below the surface.

Shallow earthquakes are between 0 to 70 km deep; intermediate earthquakes, 70 to 300 km deep; and deep earthquakes, 300 to 700 km deep.

An instance of the devastating effect of a shallow earthquake would be the 5.6 magnitude earthquake in Indonesia in Novermber 2022 that left more than 160 dead and hundreds injured as buildings crumbled and terrified residents ran for their lives on the main island of Java.

According to the U.S. Geological Survey, “There is not one magnitude above which damage will occur. It depends on other variables, such as the distance from the earthquake, what type of soil you are on, building construction” and other factors.

Why an earthquake’s depth matters

A quake’s destructive force depends not only on its strength, but also on location, distance from the epicentre and depth.

Quakes can strike near the surface or deep within the Earth. Most quakes occur at shallow depths, according to the U.S. Geological Survey.

Shallow quakes generally tend to be more damaging than deeper quakes. Seismic waves from deep quakes have to travel farther to the surface, losing energy along the way.

Shaking is more intense from quakes that hit close to the surface like setting off “a bomb directly under a city,” said Susan Hough, a USGS seismologist.