Large parts of a glacier break off and crash down a steep mountainside, dragging boulders, rocks, gravel and soil with them.
The raging force of the growing mass generates heat that melts ice into water, which mixes with the mushy mass of rock, soil, debris and mud. The current drags terrain, houses, roads and bridges along the valley floor.
This is the presumed sequence of events that led to hundreds of lost lives and destroyed villages, towns and infrastructure in Nepal on the slopes of the Himalayas on Wednesday, according to the US Geological Survey (USGS).
Such events occur at regular intervals and have probably increased in scope in line with global warming, which causes glaciers to retreat, become unstable and lose mass, says Mats Eriksson, head of department at the Swedish Geotechnical Institute.
Risk in mountain environments
This in turn creates more glacial lakes in the mountains that dam up behind unstable ridges, moraine ridges in the valley. If they rupture, powerful tidal waves are created that can drag entire villages down in a devastating mudflow.
We will certainly experience more similar events in the future, says Mats Eriksson.
Other experts and researchers also see a connection between floods like the one in Nepal on Wednesday and global warming.
Dorothy Heinrich, a meteorology researcher at the University of Reading in the UK, told the AFP news agency that climate change tends to manifest itself in the form of these types of disasters.
According to Mats Eriksson, there is a risk of similar floods everywhere in mountain environments with glaciers, such as the Alps, the Himalayas and the Andes.
Keep an eye on the glaciers
How can humans then protect themselves from such disasters?
It is important to have a good understanding of how glaciers retreat, according to Mats Eriksson.
In rugged terrain, satellite images and field visits can be used to monitor the retreat of glaciers, he says.
