How a collapsing glacier may have caused the catastrophic Nepal floods

A devastating series of deadly flash floods has destroyed villages in parts of Nepal and Tibet , with hundreds missing, including some Canadians, as experts say a falling glacier likely triggered a chain reaction of catastrophic events that could get worse in the coming days.

According to the U.S. Geological Survey, a magnitude 5.2 seismic event occurred near the border between Nepal and Tibet, an autonomous region of China, on Aug. 26 at 8:37 a.m. local time.

The event was initially reported as an earthquake, but additional analysis determined the seismic event was caused by a glacial collapse that is believed to have resulted in the flow of debris that caused “catastrophic impacts downstream.”

“It is biblical — the amount of power when we get ice falling large distances. The amount of kinetic energy is really enormous. And when it hits the water, it just produces these incredible floods downstream. It’s hard to imagine that devastation,” says Kent Moore, a professor of atmospheric physics at the University of Toronto.

“A lot of these glaciers are what are called hanging glaciers, and so they’re kind of on very steep slopes and they’re frozen onto the rock. As the area warms, that adhesion with the rock is becoming less strong, and so there’s a greater kind of tendency for these avalanches to occur.”

The death toll is so far believed to be at least 353 with more than 1,300 people missing as of Thursday, including roughly 30 Canadians.

Images showed what appeared to be the second floors of buildings in hard-hit Nuwakot district slathered in mud after the torrent rushed by. Debris hung from tree branches and wires, vehicles were buried and stunned survivors were caked in mud.

“It seems like the front of a glacier broke off, got mixed up with landslide debris, and then suddenly reached the river below without anyone knowing that this would be a source of risk in the past,” says Luke Copeland, professor and glaciologist at the University of Ottawa.

Although glaciers breaking off of mountains has occurred in the past, including in the Himalayas, Copeland says, “this one really took people by surprise. It was an area that wasn’t being monitored, and wasn’t expected to occur in this location.”

Warming temperatures worldwide as part of climate change are leading glaciers, ice sheets and shelves and permafrost to recede or defrost rapidly. In areas of high altitude, like the Himalayas, glaciers and other ice formations are losing their grip on steep mountain slopes and the risk of them falling is increasing as a result.

Slobodan Simonović, director of engineering works and professor emeritus with the Institute for Catastrophic Loss Reduction at Western University says there are four main reasons the glacier in the Himalayas likely broke off and fell, causing the chain reaction of devastation.

“One is the precipitation and obviously the monsoon season that is occurring right now. The second one is the topography and kind of geology of the region, where you have a very steep slope, very unstable land that can easily be moved when more moisture or more water is reaching it.