Massive landslides and flash floods on the Nepal-Tibet border have caused widespread damage and left hundreds dead or missing.
Search and rescue operations are under way.
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operations → cause → way
Chinese state media has said there are significant casualties, while Nepalese officials anticipate "huge scale loss".
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officials → say → loss
Here is what we know so far.
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we → know → what
What caused the deadly landslide?
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What → cause → landslide
Nepal's foreign minister initially said an earthquake was reported on the Tibet-Nepal border shortly before the landslide, suggesting it may have triggered the disaster.
The United States Geological Survey (USGS) had first reported the event as a magnitude 4.4 earthquake on Wednesday, but later confirmed the incident "was instead a glacial collapse and debris flow" that "caused subsequent catastrophic impacts downstream".
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that → say → impacts
"Additional analysis of nearby seismic stations, long period seismic waves, and satellite imagery led to the determination that the seismic event was instead a glacial collapse and debris flow, and that no earthquake had occurred," USGS said on Thursday.
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USGS → lead → Thursday
Earlier Nepali authorities had also told the BBC that a massive chunk of ice may have collapsed from a mountain, pulling down rocks and other sediments with it.
uncertain
chunk → tell → it
Climate change is known to be driving faster glacier melt in the Hindu Kush Himalaya region and, as rescue efforts continue, scientists are trying to piece together the exact order of events.
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scientists → know → events
Simon Cook, senior lecturer in energy environment and security at the University of Dundee who specialises in glaciology, said "climate change could have an impact".
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change → specialise → impact
Cook said his team had detected that the lower part of a glacier in Nepal near the Langtang Lirung peak - which is approximately 15km (9 miles) west of the site of the floods - had collapsed.
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which → say → floods
He estimated that the glacier collapsed in a northwesterly direction and then travelled westwards downstream.
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glacier → estimate → direction
He told the BBC "permafrost is partially holding some mountainsides together, this permafrost is warming and thawing and degrading so you are going to get more landslides".
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you → tell → landslides
Mike Searle, professor of Earth sciences at Oxford University, said the glacier could have collapsed "hours or days" before the flooding hit Nepal and Tibet.
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flooding → say → Nepal
He told the BBC: "I think the sheer wave of debris suggests there was a landslide first, the water built up, (which) dammed the river, and then it burst in one huge great flood."
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it → tell → flood
One possibility is that water from rainfall or melting ice may have destabilised the ground or ice, triggering a chain reaction.
uncertain
water → melt → reaction
Scientist will be looking at satellite images of exactly where the landslide occurred, whether any glacial lakes suddenly drained, and where the river might have become blocked, as well as data on recent rainfall.
uncertain
river → look → rainfall
A deluge of material careered towards northern Nepalese towns, including areas popular with mountaineering tourists and pilgrims.
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deluge → career → tourists
Footage showed a wall of mud and rock sweeping away buildings, roads and vehicles, as people fled the fast-moving wave of material in the Nuwakot region.
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people → show → region
In one video, a towering wall of water and mud was seen rushing down a gorge along the Trishuli River and enveloping the Rasuvagadhi Border check point, a multi-storey building.
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wall → tower → point
Severe flooding has been reported along the Bhote Koshi, Trishuli and Narayani rivers.
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flooding → report → rivers
Deaths have also been reported in villages on the Tibetan side of the border.
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Deaths → report → border
The International Centre for Integrated Mountain Development (ICIDMOD) has warned secondary flooding could occur in the coming days as a result of the debris that washed into the river systems.
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that → warn → systems
In a report, the ICIDMOD said they are in the process of assessing whether the Trishuli River has been temporarily blocked in narrow sections.
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River → say → sections
If it has been blocked, it is at risk of forming a landslide dam - and a second flooding event.
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it → block → dam
Authorities and scientists are continuing to evaluate the size, location and stability of any potential blockages.
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Authorities → continue → blockages
How many people are dead and missing?
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people → miss → ?
The number of people killed or missing is still becoming clear
Nepali police say at least 332 people have died.
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people → kill → becoming
Among those killed, 64 were found in downstream areas in the Chitwan district while another 26 were found in Nawalparasi East.
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26 → kill → East
In an update on Thursday morning, Nepal's National Disaster Risk Reduction and Management Authority said 826 people are still missing, including more than 529 tourists, with 466 foreigners among them.
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people → say → them
Meanwhile, China's state broadcaster CCTV said on Thursday that the number of people missing in the mudslide disaster in Tibet's Gyirong county had risen to 558.
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number → say → 558
Among these are 260 foreign nationals, CCTV said, adding that the death toll remained at three.
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toll → say → three
The Nepal Tourism Board said on Thursday that 644 tourists are still missing, 33 of which are UK nationals.
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33 → say → which
It is not clear if any of the missing in the Nepali and Chinese figures have been counted twice.
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any → miss → figures
How are governments responding?
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governments → respond → ?
Nepal's prime minister said "the entire nation has been left shocked and deeply distressed" and that officials would coordinate with China on the response.
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officials → say → response
China's President Xi Jinping urged an "all-out" search effort, and promised stronger monitoring and early warning systems to prevent secondary impacts.
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Jinping → urge → impacts
In neighbouring India, Prime Minister Narendra Modi said his government was "prepared to provide Nepal with all possible types of humanitarian assistance".
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government → neighbour → assistance
UN Secretary General António Guterres says he is "saddened by the severe flooding", adding that UN teams and partners are mobilising supplies and personnel in Nepal to support the government-led response.
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teams → say → response
The US has promised $500,000 (£367,982) in aid which will be used to cover emergency shelter, water, sanitation and other relief items for communities affected by the floods.
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which → promise → floods
Prime Minister Andy Burnham said the UK has offered £5m to help the Nepalese government and will do "everything we can" to support British nationals in Nepal.
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we → say → Nepal
…and 4 more, not listed.
The Aporia
