Mild tremors were felt in Calcutta on Tuesday morning as a powerful earthquake hit a remote region of Tibet and parts of Nepal, causing deaths and damage.

Tremors were felt across south and north Bengal but no casualties were reported from the state.

A professor of seismology said the epicentre of the quake was too far from Calcutta to have any substantial impact on the city.

The National Centre for Seismology (NCS) said the earthquake struck at 6.35am and its epicentre was in Xizang in Tibet Autonomous Region, near Nepal’s border, at a depth of 10km.

Minutes later, a Facebook user by the name of Jai Prakash posted: “Earthquake in Kolkata just now at 6.40.a.m. approx”. It was accompanied by a clip of an oscillating ceiling fan.

“Jolted by a quake. Was on for about 25 seconds or so. Folks, be safe,” said a post on X.

Many did not feel anything. “I was up at 6am today. I spent almost 40 minutes on the balcony. But I did not feel anything,” said Ananya Mukherjee, who lives on the 14th floor of a high-rise in Garia, off EM Bypass.

At least 95 people were killed and 130 injured in Tuesday’s earthquake, according to several media reports. The city nearest to the epicentre was Shigatse, the second-largest city in Tibet and close to the border with Nepal. Several parts of north India were jolted by tremors.

“For Calcutta, it was a far-source earthquake as the epicentre was more than 500km away. A near-source quake is one where the epicentre is within 200km and an intermediate-source, where the epicentre is between 200km and 500km,” said Sankar Kumar Nath, vice-chancellor of Burdwan University and former professor of geophysics and seismology at IIT Kharagpur.

In seismic parlance, a quake of magnitude 5 qualifies as “strong”.

On December 2, 2023, very mild tremors were felt across Bengal, including Calcutta, as an earthquake hit neighbouring Bangladesh. No casualties were reported here. The quake, measuring 5.6 on the Richter scale, had its epicentre 48km southwest of Comilla in Bangladesh.

The Nepal quake in April 2015, which killed many, measured 7.8 and was classified as “major”. The epicentre was over 900km away but tremors were felt in Calcutta.

On November 4, 2023, a 6.4 magnitude earthquake struck Nepal again, killing more than 150 people. Buildings as far as Delhi shook. But Calcutta did not feel any tremor.

The Richter scale stays constant in all places a quake is felt, but the damage potential varies depending on the distance from the epicentre.

Geologists believe Calcutta’s vulnerability to a major quake epicentred nearby is high because of its alluvial or unconsolidated soil, the kind of soil in which earthquakes tend to cause extensive damage.