Cracks in a building in Durgapur. Picture by Rana Ghosh

Feb. 6: Two persons were injured and over two dozen mud houses collapsed when a “slight-magnitude” earthquake shook parts of south Bengal this morning.

The tremor had its epicentre between Indpur and Onda blocks in Bankura, 200km from Calcutta. It occurred around 11.40am and continued for three to six seconds.

“It was a slight-category earthquake and measured 4 on the Richter scale,” said G.C. Debnath, director of the weather section at the Regional Meteorological Centre at Alipore in Calcutta.

“It is a low-magnitude earthquake in which the chance of damage is less,” Debnath said.

Cracks appeared in about 20 buildings in Bankura, Burdwan, Birbhum, Purulia and West Midnapore.

A 22-year-old resident of Bishnupur in Bankura was grievously injured when clay tiles slipped off the roof of his mud house and fell on his head. He was given six stitches.

Bulu Chakraborty, 55, was working at a construction site in Bankura’s Gangajalghati when a brick fell on her right arm and fractured it.

Several railway cabins in Andal, Durgapur and Panagarh had cracks on the walls. Authorities at Eastern Railway’s Asansol division ran an inspection locomotive from Asansol to Panagarh after the quake but found the tracks intact.

“I was cooking dal in the kitchen when I felt the floor shake. I was alone in my ground floor flat and ran out immediately,” said Chaity Chatterjee, 22, a housewife in Durgapur.

Jhumpa Mistry, 14, of Durgapur was in school when the quake left her unconscious. “We were waiting for our teacher in our ground-floor classroom when the floor started shaking. Everyone ran out. I got nervous and fainted,” Jhumpa said from hospital.

Seismologists said there was no reason to panic anymore. Such a “slight-magnitude” quake is not typically followed by aftershocks.

However, an aftershock was felt in Mejia, Gangajalghati, Barjora, Bankura town, Indpur and Onda in Bankura and in Ranigunj in Burdwan this evening.

R.S. Dattatreyam, director of seismology at the India Meteorological Department, New Delhi, had earlier said that in the absence of aftershocks, such an event could not be linked to an underground fault.

“It was an isolated event in a zone of relatively low seismicity,” he said.

The epicentre of today’s quake lay at 23.6 N latitude and 87.1 E longitude, which falls in zone-3, a region where the maximum possible force of an earthquake can reach up to 7 on the Richter scale. Calcutta falls on the boundary of zones 3 and 4, where it can touch 8.

Scientists said damage from earthquakes depends on several factors in addition to the magnitude. These include local underground geological features and adherence to building codes specified by the Bureau of Indian Standards.