Large Landslide in British Columbia, Canada

On August 6, a melting glacier in British Columbia, Canada, was reported to have triggered a massive muddy landslide at 5:30 a.m. Later reports, still somewhat confusing, say that it was actually the Capricorn glacier itself that gave way. The area affected is about 150 miles north of Vancouver, British Columbia.  This is an area of unstable volcanic rocks prone to landslides.  The estimated volume of the slide is estimated to be 40 million cubic meters, and is the second largest slide in Canadian history, the largest being the Hope slide of 1965 that had a volume of 46-million cubic meters.  The new slide is being referred to as the Mount Meager slide.  The slide stopped in the area where Megher Creek intersects the Lillooet River, and temporarily damed the Lillooet.  A temporary lake was formed containing 1.5 - 3 million cubic meters of water, but breached through the dam early in the morning of August 7 (3:00 a.m.)  It cut a breach between 25-50 meters wide (contrast this to the on-going drama at Attabad in Pakistan). Further information is here, as well as more photos. The photo attached was taken by "Bonny Makarewicz, Special to the [Vancouver] Sun", and can be found in the reference cited.

Nozzles and Debris Flows

Image from The Province.

The town of Oliver in the Okanagan, a rural area of British Columbia, Canada, was hit by a mud and debris flow yesterday, June 13.  This flow originated in an incised canyon where Testalinda Creek flowed from a lake.  Five homes were swept off their foundation, there were no injuries.






As pointed out on Dave's Landslide Blog (on June 14), Oliver sits on a small debris fan, shown as the triangular area just above the highway 97 sign in this photo from Google Earth (click on the photo to enlarge it so that you can actually see the debris fan). Upstream from Oliver is a lake, drained by Testalinda Creek which flows in a deeply incised canyon.  In such situations, debris can build up at the bottleneck in the canyon to effectively form a dam. When rain has saturated the soil, as has been the case this rainy summer, the debris pile can let loose and send a torrent of water, mud, and debris out into the surrounding country side.