Image of the Day:
Valley of the Rocks Avalanche: The Largest Landslide in North America
Valley of the Rocks, B.C., Canada. A geologist says the largest landslide in North American history, a colossal avalanche of rocks and earth, occurred on a Rocky Mountain slope near the B.C.-Alberta border some 10,000 years ago. The huge avalanche permanently shifted the geography of North America.
Photo (undated): Nick Roberts, Simon Fraser University.
A detailed study of the cataclysmic event has been carried out by researchers Nick Roberts of Simon Fraser University and Steve Evans of the University of Waterloo.
“Despite its size, this landslide has gone virtually unrecognized” in the scientific literature, Roberts told Canwest News Service. “Even basic information about the rock avalanche, including its precise dimensions, volume and age,” were unknown until now.
“Destabilized by forces associated with retreating glaciers at the end of the last Ice Age, the final cleaving of the mountain above the Valley of the Rocks might have been triggered by an earthquake or a torrential rainstorm, the researchers believe.” The report said.
What was the magnitude of the avalanche?
“When the mountain gave way, any Stone Age hunters in the vicinity might have been convinced the end of the world was unfolding.” The report said.
“Transfer of kinetic energy to sound energy through fracturing and collision of rock material would have produced a tremendous noise,” says Roberts.
“Survivors of large landslides in recent decades have described sounds similar to cannon fire or the roar of a jet engine,” he adds, noting that the blasts likely represent “initial fracturing in the first stages of failure” while the roar is generated by the rush of millions of tonnes of rock down the mountain side.
“In the case of the Valley of the Rocks avalanche,” says Roberts, “these sounds would have been deafening within a few kilometres of the landslide, and would have been audible for at least many tens of kilometres.” More…
Related Links:
- Landslides [FEWW Index page – also search blog entries not yet indexed, using “mudslide,” “landslide,” “quake,” and “earthquake” ]
- Landslides USGS (index page)
- Recent Landslides (USGS index page)
- Floods [Index page]
Research Papers:
- Hazard and risk from large landslides from Mount Meager volcano, British Columbia, Canada
- Legacies of catastrophic rock slope failures in mountain landscapes
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