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Scientific teams are yet to begin their investigation into the cause of last Sunday's flash flood in Uttarakhand, India, which killed 32 people with another 171 missing.
But new evidence suggests that the incident may have been caused by a breach in a temporary pool or lake formed by obstructions due to landslides or snow avalanches - an event described as a Landslide Lake Outburst Flood (LLOF).
Satellite images circulated among scientists tracking the incident show that a large chunk of fresh snow from a mountain near Raini village in Chamoli district fell on Sunday, possibly becoming the reason for the flash flood, reported The Indian Express.
The resulting avalanche could have released about 4 million cubic metres of water in the rivers.
"Our preliminary investigation through satellite imaging has pointed to the possibility of the flood having been caused by the melting of snow, and not a glacial lake outburst," said Mr Santosh Rai, head of the Glaciology and Hydrology division at the Dehradun-based Wadia Institute of Himalayan Geology.
"Of course, we need to investigate this further. We have sent two teams of scientists to the site and will have more accurate information when the investigation has been completed."
A member of the probe team said the new evidence clearly indicates that Sunday's incident was a result of a landslide or snow avalanche.
"The possibility of this being an LLOF event does seem more likely after the emergence of the satellite images," he said. "A landslide or snow avalanche can create obstructions in the normal path of a flowing river or stream, which results in the formation of a temporary pool or a dam-like situation.
"When this obstruction finally gives way to the force of accumulating water, it creates a situation similar to a lake burst. In the case of an avalanche, snow adds to the volume of water."
Earlier, the flash flood was believed to have been caused by a Glacial Lake Outburst Flood or a breach in a proglacial lake that forms at the tip of a glacier that is retreating due to rising temperatures. The big question mark in that theory was that scientists did not know of the existence of any such lake in the area.
The disaster has also been blamed on rapidly melting glaciers in the Himalayan region caused by global warming. Building activity for dams and dredging riverbeds for sand - for use in the construction industry - are other suggested factors.
The Press Trust of India reported that army, paramilitary and rescue personnel are working non-stop to locate 171 people, mostly labourers working at two power projects, who are reportedly missing.
Officials said rescue operations are centred on a 1,900m-long tunnel at the Tapovan site, where at least 35 people are believed to be trapped.
Twelve people were rescued from one side of the tunnel on Sunday.
According to the Uttarakhand police, the avalanche struck at about 11am local time on Sunday, destroying a dam known as the Rishiganga Hydroelectric Project. The impact catapulted water along the Dhauliganga river, damaging another power project downstream in the Tapovan area.
Senior police officials said a bridge in Tapovan that connected 13 villages was washed away. Videos showed the floodwater barrelling through the area, leaving destruction in its wake.
Emergency crews rescued 16 workers who had been trapped inside a tunnel filled with debris.
One of the workers was Mr Rajesh Kumar, 28, who together with others clung to scaffolding rods in the tunnel for four hours before the water level fell and they were able to escape.
"Suddenly there was a sound of whistling... there was shouting, people were telling us to come out. We thought it was a fire. We started running but the water gushed in. It was like a Hollywood movie," he said from his hospital bed.
"We just kept telling each other - come what may, we must not let go of the rods."
AFP, Indo-Asian News Service
