A fully-grown krishnachura tree on a footpath of Tollygunge’s Pratapaditya Road crashed on the wall of a two-storey building across the road on Wednesday morning.

Two other trees got tilted in a dangerous way on Biren Roy Road in Behala and on DC Dey Road in Tangra.

The trees fell or tilted despite the fact that the city was not buffeted by very strong winds or heavy rain under the impact of Cyclone Yaas, which made landfall around 250km away in Odisha.

The highest wind speed Calcutta experienced was 62kmph, around 6.30am. The consistent wind speed in the city was less than 50kmph, not strong enough to tilt or uproot trees, police officers said.

The krishnachura tree that collapsed on Wednesday grew on a patch of soil on the concrete footpath.

Naturalist Arjan Basu Roy, who runs an NGO that works for restoration of trees, said the krishnachura tree might not have fallen “as suddenly as it appeared”.

“There could be several factors (responsible for the collapse of the tree). Most of the trees are planted unscientifically without giving their roots enough space to flare. Trees should get at least a 2-metre radius to grow properly. Otherwise, the roots cannot grow properly,” he said.

Branches of a tree that fell during the storm being cleared on Wednesday. Picture by Pradip Sanyal

A tree can fall even when there is no storm, said Basu Roy.

“Sometimes, if the roots are weak, even a consistent nagging force is enough to uproot it, especially if the soil is wet,” he said.

At least 10,000 trees had been uprooted in Calcutta and its adjoining areas during Amphan, the cyclone that ravaged the city at an average speed of 100kmph, with gusts clocking 133kmph.

Several rescue teams were on stand-by on Wednesday to cut and trim trees and clear roads across the city.

A team of the National Disaster Response Force stationed in Tollygunge and the police were alerted about the krishnachura tree around 9.30am.

“We were a little surprised to see the tree. The entire tree was uprooted and it was neither raining nor windy. The krishnachura tree had a thick trunk… it had crashed on the boundary wall of a house on the other side of the road. Luckily, no one was injured,” said a member of the

unified command, which was set up to coordinate relief and rescue operations involving multiple agencies across the city.

The tree trunk was sliced into pieces and removed from the thoroughfare. The entire operation was over in 30 minutes.

The trees that got tilted in Tangra and Behala were trimmed by the Disaster Management Group personnel and cops of the Diamond Harbour traffic guard, respectively.

At least 14 cases of tilted trees and branches falling on roads were reported from across the city till Wednesday evening.

There were no reports of anyone being injured, the police said.