People rush out of their offices as earthquake jolts Kolkata on 12 May, 2015.IANS

After another major earthquake rattled Nepal on Tuesday, seismologists warned that Kolkata may witness a massive quake in future. They said a fractured zone lies just 4.5 km beneath the city and every time the ground shakes, the capital of West Bengal moves towards Dooms Day.

Although the fracture, known as Eocene Hinge Zone, has been inactive for years, it is capable of triggering a massive earthquake when it turns hyperactive, experts said. It may result in an earthquake measuring not less than 6 on Richter scale.

"This could turn the 300-year-old city in to rubble within minutes. It's just a matter of time," said Supriya Mondol, Associate Professor with Jadavpur University and expert in plate tectonics and quakes, Hindustan Times reports.

As the fractured "faultline" lies exactly beneath the centre of the city and not on the edge of tectonic plates near Nepal, Kolkata has not suffered any major quakes but has been experiencing minor jolts constantly.

When the energy accumulating along the fractured zone will try to release through the faultline, it will trigger a massive earthquake, said an expert. Explaining it further, another seismologist and IIT Kharagpur professor Sankar Kumar Nath said Nepal and Burma were good examples of such a case.

"But the Indian plate, which contains the faultline, is continuously pushing northwards and sliding beneath the Eurasian plate at a rate of 40mm each year. This is what resulted in the Nepal earthquake. The Indian plate is also pushing against the Burma plate, which triggered the 2004 tsunami," Nath said.

He added that the two massive earthquakes in Nepal that triggered several aftershocks in India have caused continuous stress on the Hinge Zone, which might turn hyperactive and set off a strong quake in Kolkata. But when will this happen is still not known.

"This continuous stress and strain - the Indian plate rubbing against two others - could turn the faultline below Kolkata into a hyperactive zone and trigger a massive earthquake in future. The energy thus liberated will be so huge that it'll trigger an earthquake measuring not less than 6 on the Richter scale. I leave it to you to guess what the results will be," he added.

Even the quake of magnitude 6 on Richter scale, with epicentre beneath the middle of the city, is strong enough to turn the city into rubble, believes a senior official at Kolkata's Indian Meteorological Department (IMD).

"The city had a close shave on both April 25 and Tuesday. The tremors felt in the city were not more than 5 on the scale. Kolkata won't be able to withstand an earthquake beyond 6. A quake measuring 6 would kill a few lakhs and bring down several old and quite a few new multi-storeyed buildings," the IMD official said.