Dramatic Nepal Flood Footage Shows Bus-Sized Boulder Swept Through Streets as People Flee at Last Second

Dramatic new video from Nepal has laid bare the scale of destruction left behind by Wednesday’s devastating flood.

Hundreds of people have been killed or remain unaccounted for after a sudden flash flood struck the Nepal-Tibet border on Wednesday morning, flattening homes, submerging roads and tearing bridges from their foundations.

Nepali officials said rescue teams have recovered the bodies of at least 332 people, with more than 800 others still missing as emergency operations continue.

Across the border in China-controlled Tibet, authorities said 558 people remain missing and three have been confirmed dead. It is not yet clear whether any of those cases overlap with the toll reported by Nepal.

Survivors caught in the disaster recorded harrowing footage showing the force of the floodwaters and the damage left across the region.

One clip filmed in the mountainous country shows a torrent of water surging through a densely built town.

Amid the thick, muddy floodwater, a massive boulder can be seen slowly rolling through the valley settlement.

Shocked residents filmed the enormous rock as it moved past their homes, while also documenting the widespread devastation caused by the flash floods.

Flood water had spread for several hundred metres across the valley, with trees bowing due to the sheer force of the water. 

Another terrifying clip showed petrified workers who were operating near a river running for their lives to escape the flood. 

Scores of men in orange hi-vis jackets and hard hats fled in terror as they watched the mass of water rush at them. 

One foolhardy man who stopped to film the flood quickly realised how dangerous it was and ran in fear from the water while screaming ‘oh my god’ over and over again. 

As the men managed to get to higher ground, the water that was rushing through the river was heard violently crashing. 

The man filming the incident turned around to witness a huge plume of water fly into the air. 

Upon seeing this the workers decided to abandon their path up a winding, muddy road, instead choosing to clamber up precarious rocks to get to higher ground as quickly as possible. 

Further down stream, people living in a small riverside village were forced to watch in horror as the tsunami-like wave thundered towards their homes. 

As the surge of water twisted down the river, onlookers screamed in terror as it came hurtling towards them.

The river quickly burst its banks as the water, carrying debris from upstream, came closer. 

Nearby farms were quickly flooded with a thick sludge of muddy water. 

Within just a few minutes, the banks of the river were completely submerged as the whole area flooded. 

Another clip, this one taken from a more densely populated town, showed the water rising quickly and surging over a bridge in the centre of the settlement. 

Horrified locals could do little more than watch or run in terror. The panicked drivers of vans and cars were heard blaring their horns, desperate to get away from the water. 

Within just a few seconds, the bridge was swept away by the sheer force of the water.  

A glacier collapse in Nepal’s mountains near Tibet appears to have triggered the disaster.

‘A large chunk of glacier fell from about 5,200 metres (about 17,600 feet)… into a valley,’ said Simon Cox, principal scientist at New Zealand’s GNS Science.

It ‘transformed into this raging mass of debris… where it picks up rocks and sediment and trees and anything in the way and fires it on down through the canyon,’ he told AFP.

The wall of water first hit  a border post, as documented in terrifying CCTV footage showing mud and debris engulfing the area as people fled before it.

It then travelled downstream into Nepal, flooding villages and bringing down bridges and buildings. 

The glacier collapse was large enough to register as a seismic event, initially mistaken for an earthquake.

But after further analysis, the US Geological Survey determined ‘that the seismic event was instead a glacial collapse and debris flow, and that no earthquake had occurred.

The collapse registered as a 5.2-magnitude ‘seismic event’, which took place at 8:37 am local time.

Estimating just how much of the glacier collapsed will take time, Cox said, but it could range from ‘half a million cubic metres to tens of millions of cubic metres.’ 

With the affected area largely inaccessible, experts are using satellite imagery and any available measurements on the ground to reconstruct the disaster.

‘We can look at satellite imagery taken before and after the event, and try and see what has changed, essentially looking for what is missing from the mountains in the ‘after’ imagery’, said Lauren Vargo, a glaciologist at New Zealand’s Victoria University of Wellington.

Soon after the seismic activity was recorded, a nearby water monitoring station stopped transmitting, Nepali authorities said.

Stations downstream began going offline one by one, though water was registered reaching up to 12.3m high in Kalikhola, near the Tibet border at 2.14pm, they added. 

Early speculation suggested a glacial lake outburst flood, or GLOF, a growing risk as glaciers melt due to climate change.

A GLOF occurs when a fragile debris wall holding back a lake of glacier melt suddenly collapses, unleashing the water behind it.

Some experts suggested a GLOF might have been involved.

‘Water does flow within glaciers and flows beneath glaciers,’ said Adrian McCallum, a glaciologist at the University of the Sunshine Coast.

‘But to my mind, the only reason why a large volume of water should all of a sudden flow down a valley is because it has been released,’ he told AFP.

Other experts said they did not detect existing glacial lakes near the site of the glacier collapse, and theorised that water collected under the glacier might have cascaded down with the falling chunk.

The falling glacier ice could also have briefly dammed the river, collecting water behind it that was released when it dislodged.

Summer glacier melt upstream and monsoon rains would mean the rivers were already high, and the volume of water was also swelled by debris and mud picked up as it travelled kilometres from the initial collapse, added Mr Cox.  

Nepali authorities first received word of a flood around 9.00am local time, and began alerting areas along the Bhote Khoshi river to ‘stay on high alert and stay in safe areas’.

But it is unclear how many people received the warning, or how much time they would have had to respond.

‘The reality is, if you are in a community underneath a large glacier and potentially a glacier lake where a GLOF could occur, then to some extent, it’s a ticking time bomb,’ said Mr McCallum.

And even for those receiving a warning, options would be limited, said Hatim Sharif, a hydrologist at the University of Texas San Antonio.

‘Running will not help,’ nor will trying to flee by vehicle, he told AFP, because the mud and water moving at high speed form a lethal combination ‘like liquid concrete’.

The only solution is to climb up a hill, at least 20ft, he estimated. 

While it is hard to immediately attribute any individual glacial event to climate change, the warming planet is a constant background stress on these ancient ice rivers, experts say.

Glaciers are retreating globally, creating disaster risks but also depriving downstream communities of vital water sources.

‘The biggest way to mitigate the risk would be to reduce our greenhouse gas emissions to limit warming,’ said Ms Vargo.