Why even 4.4-magnitude earthquake gave a big jolt to Delhi

In the aftermath of the earthquake, Delhi Metro trains were stopped for 2-3 minutes as a precautionary measure

An earthquake of 4.4 magnitude jolted Delhi and nearby areas on Thursday morning.

According to the National Centre for Seismology (NCS), the earthquake occurred at 9:04 am at a depth of 10 kilometres. The coordinates shared by NCS placed the epicentre at 28.63°N latitude and 76.68°E longitude.

Though classified as moderate, the tremors were strong enough to shake houses and forced people in several high-rise buildings in Delhi, Noida, Greater Noida and Ghaziabad to rush out. Videos showed the ground shaking as people watched in horror.

Authorities have reported no major damage or casualties, but the sudden tremors sparked concern among residents.

Was 4.4 magnitude too strong?

It is considered a moderate intensity quake where low-level tremors can be felt, but there is no such damage to structures.

According to Michigan Tech University, an earthquake below 2.5 magnitude is generally not felt. A quake between 2.5 to 5.4 magnitude is minor and there is usually no damage. An earthquake of 5.5 to 6.0 magnitude can cause slight damage to buildings and is strongly felt.

Why were the tremors so strong?

The key reason for the tremors to be so noticeable in Delhi-NCR was the earthquake's epicentre being located very close to the city. The epicenter of an earthquake is the point on the Earth's surface directly above where the earthquake originates.

Delhi falls under Seismic Zone IV and is prone to moderate-to-strong earthquakes, making localised tremors more pronounced. Experts have often noted that buildings, particularly high-rises, sway more due to their design, increasing the perceived intensity of shaking.

Another reason is the densely populated city area where the seismic waves travel a shorter distance and then reach the structures. This further amplifies the tremors.

The shallow depth of earthquakes is another reason behind the strong shaking as quakes that occur closer to earth's surface trigger stronger shaking.

According to the National Center for Seismology, the epicentre of the earthquake was in Haryana's Jhajjar. The earthquake struck at a depth of 10km. The epicentre was 3 km northeast of Jhajjar and 51 km west of Delhi.

The more depth, the lesser the intensity of the tremors of the earthquake, say experts.

This is not the first seismic event in the region this year. On February 17, a 4.0 magnitude quake hit the Delhi-NCR area at a depth of 5 km.

A resident of Jhajjar told ANI, "I was working in my office when suddenly the computer systems and fans started shaking. So, it was quite scary. We rushed out. The epicentre is in Jhajjar. So, we are anticipating an aftershock. I had never felt such an earthquake before."

Rajbala, who experienced the tremors in Jhajjar, said she was on the terrace when everything started shaking vigorously.

A resident of Gurugram said that he had asked everyone to rush out of the building as they felt the jolt. "We were sitting here and having tea when I suddenly felt strong earthquakes. I told everyone to rush out of the building. Everyone rushed out," he said.

In the aftermath of the earthquake, Delhi Metro trains were stopped for 2-3 minutes as a precautionary measure, in accordance with Standard Operating Procedures (SOP).

Speaking to ANI, a passenger, Arshad, said, "The train stopped around 9.04-9.05 am. We didn't feel (the tremor)."