Mountain Sides Collapse After Huge Earthquake

A powerful earthquake has triggered widespread landslides and avalanches in Kluane National Park and Reserve, according to the Yukon Geological Survey (YGS). Luckily, the earthquake happened outside of the mountaineering season.

Last week, YGS staff took advantage of a window of clear weather to fly into the remote region and assess the impacts of the earthquake. The flyby was conducted to document landslide and avalanche activity, verify satellite observations, and determine whether the earthquake caused the ground surface to rupture.

Despite evidence that the fault slipped by a few metres at a depth of roughly five kilometres, YGS found no clear signs that the rupture reached the surface. Scientists note, however, that any surface rupture could be hidden beneath glacier ice.

The earthquake triggered some big landslides, particularly on the slopes of Mount King George, a famous 3,741-metre peak located about 40 kilometres east of Mount Logan. The first ascent of King George was in 1965, read about it in the 1966 American Alpine Journal here.

When the survey team arrived, clouds of dust were still visible from a large slide that had recently occurred. Other smaller landslides were seen on Mount Vancouver, Mount Logan and nearby sub-peaks. Early findings suggest that the area of maximum fault slip, as well as most aftershocks, occurred beneath or immediately adjacent to Mount King George. In addition to rockslides, the earthquake caused extensive damage to glacial ice. As noted, seracs and icefalls were commonly broken up and toppled by shaking.

In May 2017, solo Argentinian mountaineer Natalia Martínez spent four days stranded on Mount Logan after powerful earthquakes shook the Yukon and Alaska region, triggering avalanches and destabilizing snow and ice around her high camp. Parks Canada and helicopter crews eventually reached her after weather improved, and she was safely airlifted to safety. Full story here.

“It is fortunate that this event did not occur during mountaineering season,” YGS said, noting that earthquake-triggered serac collapses and avalanches have caused fatalities in the past. The survey warns that damaged ice and persistent rockfall from landslide scars may pose new hazards for future mountaineering and skiing expeditions in the region.