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Satellite images reveal bedrock and glacier collapsed on the Nepal-Tibet border, then rivers flooded
Confirmed
In clearer images from Thursday, they said they could see that the bedrock underneath the glacier had collapsed, taking the massive chunk of ice down with it and sending boulders and ice into the valley. Geomorphologists Kristen Cook and Dan Shugar said initial images from Nepal were obscured by clouds and dust from the debris, so they could only see that part of a glacier had broken off from Langtang Lirung peak, near the border with Tibet.
“It shows the whole area without anything hidden, and we could see that, yes, it looked like there was not only this glacier that had failed, but a much larger chunk of the bedrock of the mountainside itself that had given way,” said Shugar, associate professor at the University of Calgary.
Scientists say a collapsed glacier near the Langtang Lirung peak likely caused the disaster Mike Searle, a professor of earth sciences at Oxford University, said that this whole process - from landslide to flood - could have taken hours or even days.
However, in this disaster, the whole glacier seems to have collapsed "in one go", which Searle said is "very unusual". He said Wednesday's event likely happened because of "two different processes - tectonics with the Himalayas uplifting, and then climate change with increasingly high temperatures and melting of glaciers.
The centre found that water levels in rivers downstream rose by between seven and nine metres within a span of 30 minutes, and several water monitoring stations were washed away or damaged. Shugar said it’s heart-wrenching to look downstream from there on the images, to where people were living, and see how the debris has buried villages.
But usually these are smaller chunks which temporarily block the rivers, and are easily flushed out, he said. An analysis , external by the International Centre for Integrated Mountain Development (ICIMOD), an intergovernmental scientific institution, found there could have been "an ice-rock avalanche originating from a high-altitude area".
While it is difficult to say whether any single event is caused by climate change, "when you look at the pattern of these events, you do think climate change could have an impact," said Dr Cook. Mohd Farooq Azam, a specialist with ICIMOD, said the increasing frequency of hazards in the cryosphere - or the frozen parts of the Earth - "is becoming more visible than ever before.
Searle said that Langtang Lirung, like the rest of the Himalayas, has been slowly rising due to long-term tectonic movement, where one plate has been pushing another plate up. After slamming to the valley floor, the debris maintained its momentum through the steep, narrow valley as ice melted, said Cook, at the Université Grenoble Alpes in France.
What's confirmed
- In clearer images from Thursday, they said they could see that the bedrock underneath the glacier had collapsed, taking the massive chunk of ice down with it and sending boulders and ice into the valley.
- “It shows the whole area without anything hidden, and we could see that, yes, it looked like there was not only this glacier that had failed, but a much larger chunk of the bedrock of the mountainside itself that had giv
- Scientists say a collapsed glacier near the Langtang Lirung peak likely caused the disaster Mike Searle, a professor of earth sciences at Oxford University, said that this whole process - from landslide to flood - could
- However, in this disaster, the whole glacier seems to have collapsed "in one go", which Searle said is "very unusual".
- The centre found that water levels in rivers downstream rose by between seven and nine metres within a span of 30 minutes, and several water monitoring stations were washed away or damaged.
- But usually these are smaller chunks which temporarily block the rivers, and are easily flushed out, he said.
What's still developing
- Geomorphologists Kristen Cook and Dan Shugar said initial images from Nepal were obscured by clouds and dust from the debris, so they could only see that part of a glacier had broken off from Langtang Lirung peak,…
- In clearer images from Thursday, they said they could see that the bedrock underneath the glacier had collapsed, taking the massive chunk of ice down with it and sending boulders and ice into the valley.
- “It shows the whole area without anything hidden, and we could see that, yes, it looked like there was not only this glacier that had failed, but a much larger chunk of the bedrock of the mountainside itself that had…
- Shugar said it’s heart-wrenching to look downstream from there on the images, to where people were living, and see how the debris has buried villages.
- After slamming to the valley floor, the debris maintained its momentum through the steep, narrow valley as ice melted, said Cook, at the Université Grenoble Alpes in France.
- The change in the color of the water shows how much sediment the flow was carrying, turning from greenish to very brown because it's full of mud, Cook said.
- The flooding “left a wasteland in its wake” that will take many years to recover from, said Alton Byers, a mountain geographer at the University of Colorado at Boulder.
- Byers, faculty research scientist at the university's Institute of Arctic and Alpine Research, said he thinks Wednesday's flooding is related to climate change.