By Steve Hubrecht
A huge, recent rockfall in the Columbia Valley’s Bugaboo Provincial Park has prompted the closure of part of the internationally popular mountaineering and rock climbing destination. It could possibly eventually help lead to the creation of a sort of ‘risk warning’ system for rockfalls that would be similar in scope to the forecasts put out by Avalanche Canada for avalanche conditions. Such a system, if it turns out to be possible, would be the first of its kind in the world.
The recent rockfall has transformed Snowpatch Spire, one of the most well known of the unmistakable and eye-catching peaks of the Bugaboos and has completely erased a number of famous climbing routes. It was first discovered just prior to the Christmas holiday by Edgewater guide, James Madden, who works for Canadian Mountain Holidays (CMH)’s heliski operations.
Madden was flying nearby the spires.“We could see something from across the valley and we were not sure what it was,” Madden told the Pioneer. As they got closer “we thought it might be a rockfall, but never imagined it was that big…It was surprising. It’s definitely very significant.”
An entire slab of rock had essentially peeled right off the spire and crashed directly onto the glacier below, where Madden noted it has clearly had an impact. “I don’t know the physics of it at all, but it would seem the glacier underneath was compressed, or collapsed a bit.” The exact amount of rock is difficult to gauge “but it’s quite a lot”, he said.
So far only a handful of people have seen the rockfall with their own eyes, but about a month ago, BC Parks issued a closure order, shutting off access to the part of Snowpatch Spire where the rock came off, as well as to the extensive debris field below it (see image XXX above/below/at left/at right, as appropriate for layout XXX). The nearby Snowpatch-Bugaboo Col, which is the main route for mountaineers to access the Upper Bugaboo Glacier has been designated as a ‘hazard area’.
The order is in place until July 15.
A spokesperson with the provincial ministry of environment and climate change strategy (which oversees BC Parks) told the Pioneer that the closure is in place “to ensure public safety over the immediate impacted area until more information becomes available and BC Parks can undertake a geotechnical risk evaluation”. The spokesperson said it was not possible to give an update on whether the closure will actually end on July 15 or whether it is likely to be extended, until the geotechnical analysis takes place.
About why BC Parks opted not to shut access to the Bugaboo-Snowpatch Col, the spokesperson outlined that “the hazard area remains open as it is at a sufficient enough distance from the immediate impacted zone and rock debris area to enable passage. It is labeled as a hazard area so visitors remain diligent if they are traversing adjacent to the closure area.”
Simon Fraser University (SFU) Centre for Natural Hazards Research citizen science manager, Paul Adam, is one the scientists who will be involved with studying the rockfall in the Bugaboos.
Adam explained to the Pioneer that the incident was likely the result of freeze-thaw action: several of the Bugaboo spires, including Snowpatch, have very large and very deep cracks that fill with water. When it gets cold, the water turns to ice. Because water is one of the few substances that actually expand when cooled (most expand when heated), the ice has the effect of “gradually acting like a wedge that pushes the rock apart to the point where there’s less friction holding the rock in place and then the rock falls”.
Madden had explained to the Pioneer that the day before the rockfall the temperature was about 28 degrees Celsius below zero, and that it had been quite a bit warmer only a few days prior.
Adam noted that a similar process of rock “flaking off” in huge chunks also happens at the Squamish Chief, near Squamish, but added that process seems to be more a result of the rock of the Chief seeing thermal expansion (i.e. being heated and cooled directly as a result of sun and air temperature) rather than the freeze-thaw action seen in the Bugaboos. Both areas are steep, granite rock with plenty of cracks and fissures, explained Adam and both “see a lot more rockfall than many people may realize…It presents a real hazard to climbers and the general public”.
What researchers and scientists at SFU have been doing on the Chief, and what they are planning to start doing in the Bugaboos, is gather information about rockfall events and examine the conditions associated with them.
“What we want to do is get some baseline data on the Bugs,” Adam told the Pioneer. “Measure the rocks, see what is occurring, where it is happening, and how quickly it is happening.”
To do this, SFU plans to work collaboratively with BC Parks, local First Nations, and Canadian Mountain Holidays (CMH), which operates the nearby Bugaboo Lodge. (Incidentally, Adam has a work association with CMH and has time climbing in the Bugaboos.)
The work would include everything from looking through old archival photos to figure out the history of rockfall, to determining where the major cracks are in the Bugaboos, to thermal imaging of the rock in the area, to setting up cameras to create remotely-operated photographic sites (which would provide continuous visual records of how the rocks changes), as well as setting up ‘Raspberry Shakes’ — miniature seismographs (earthquake measuring devices) that are small enough to fit in the palm of a person’s hand, but which have a limited range (up to about five kilometres) in which they can reliably measure rock movement. The researchers also want to develop tiny weather stations to collect meteorological data.
A blip registering on a ‘Raspberry Shake’ stationed inside the Conrad Kain hut or Bugaboo Lodge (or even possibly outdoors somehow at the Applebee Dome campsite) could indicate rocks falling off the face of Bugaboo Spire or other nearby peaks. Researchers could then check the visual images from the cameras to figure out where exactly the rockfall was and its size.
SFU scientists want to learn in the Bugs what they’ve already learned on the Chief, by finding out where the ‘hot spots’ are. In the case of the Chief, hot spots is both a figurative and literal term, since the granite on the Chief gets very hot, temperature-wise. But, interestingly, not all parts of the rock are equally hot.
“What we’ve figured out, and this is preliminary and will be studied further, is that overhangs seem to be hotter than vertical areas (on the Chief),” explained Adam. Some overhanging parts of the Chief are actually several degrees hotter than nearby sections of straight rock. Overhanging sections of a rock climbing route present intriguing technical challenges for rock climbers. But since they are hotter than other surrounding parts of the rock, overhangs are also, it turns out, more subject to thermal expansion. This acts in conjunction with the greater forces of gravity (because overhangs, by definition have nothing underneath them) to increase the likelihood of rockfall.
“We’d like to do the same with the Bugs — to study them and figure out what’s going on there,” said Adam.
Most rockfalls are caused quite simply, by the sheer force of gravity. Through various geologic and environmental processes, pieces of rock in the Bugaboos, on the Chief, and elsewhere around the world at places such as Yosemite, get to the point that they are not directly supported by the peaks they are ostensibly part of, but are instead predominantly held in place by friction.
So then, what factors are at play when friction is finally overwhelmed by gravity?
It seems for the Chief that heating of the rock itself, and the associated thermal expansion, as well as the roots of trees growing in the cracks there, may play a role — possibly a big role — in speeding up the process involved in this gravity-friction battle. Adam suspects freeze and thaw and thermal expansion may play a similar role in speeding up rockfall processes in the Bugaboos, but is curious to find out if this hunch is accurate, as well as to find out what other factors are involved there.
A possible final outcome of this research is the creation of a risk-level warning system for rockfall. Adam is quick to caution that such an idea is only theoretical at this point and may not turn out to be realistically practical. Still, if it were to come fruition, there could be a considerable upshot from a public safety perspective.
Adam outlined that the idea is roughly similar to Avalanche Canada’s avalanche risk forecasting system. Like the avalanche system, the rockfall warning system would necessarily be more about general risk conditions instead of about specific individual hazards.
“I obviously couldn’t say exactly when or where a rockfall is going to occur, but rather could give an idea about the conditions at a given point in time. The aim would be to be able to give people a warning about what the level of risk might be,” said Adam.
So, for instance, such a system might point out that during a particularly hot, sunny stretch of summer that overhanging parts of the Chief had become significantly hotter than their typical summer average, theoretically raising the risk of rockfall. Climbers wishing to reduce their own exposure to risk while climbing the Chief could then, at their choosing, avoid overhangs and stick to purely vertical and shady routes.
The role climate change plays in rockfalls is something else that has piqued the interest of the SFU scientists. There are, for example, are trees growing in cracks on the Chief and their expanding roots systems act as a wedge prying the rock apart. In the future, if the climate continues to warm, there may be more trees and they may grow faster, which could affect rockfalls there. Climate change may also exacerbate freeze and thaw cycles in the Bugaboos, making such cycles more frequent and thereby speeding up wedging. And, who knows, possibly in the future there may even be trees growing in the cracks on the Bugaboo spires as a result of climate change.
SFU scientists are also keen to get a better handle on precisely how much rockfall is happening in the Bugaboos. “Anecdotally there is a lot of it, particularly on Pigeon Spire and the Howser Towers, but we don’t exactly know how much is happening,” said Adam. They already heard about the big rockfall, but also want to know about smaller ones. Even a single fall rock about a half metre in size can have an effect, if it falls far enough and gathers speed.
Does the SFU team, based on the photos its seen, know how much rock came down in the fall off Snowpatch Spire? Adam said the team is in the process of making an estimate, but that clearly it was “a very substantial portion of the mountain”.
Enough rock fell that it made a noticeable impact on the ice sheet below, and that too, intrigues the SFU scientists. “We’ve heard it dented the glacier,” said Adam, adding the SFU team doesn’t know much about that geomorphic process, but wants to study it more.
“We’re very interested in that. Because if you drop a rock in water, of course the water moves. It makes sense that ice would be the same, but until this incident (in the Bugaboos) it’s something we haven’t thought (about),” explained Adam, adding the Snowpatch rockfall was quite unique in that the rocks did not roll, bounce or tumble off the mountain and then slide onto the glacier (as normally happens when rockfall ends up on a glacier). Instead, owing to the sheer vertical nature of the spires in the Bugaboos, the rock fell straight onto the glacier, uninterrupted.
“It was a direct hit, in that sense. That’s different. So we want to take a look at the deformation issues that it may have caused in the ice. How did it (the ice) change?” explained Adam.
He highlighted that both the Bugaboos and the Chief are very popular rock climbing destinations, known throughout the world and drawing visitors from around the globe. “They are important to the communities near them,” he said (meaning the municipalities of the Columbia Valley in the case of the Bugaboos, and Squamish in the case of the Chief). This in turn, he explained, makes it important to understand what is happening at these granite ports of call in terms of rockfall and the hazard that presents to climbers and other members of the public.