Bingham Canyon Mine Landslide; the Largest Non-Volcanic Incident in North America’s Modern History

The April 10 massive landslide at Kennecott's Bingham Canyon mine is considered to be the largest non-volcanic incident in modern North American history and the most expensive occurrence, surpassing the costs of the 1983 Thistle slide, according to a University of Utah Study.

The landslide is also the first known to trigger 16 small earthquakes.

"This is really a geotechnical monitoring success story," Kris Pankow, associate director of the University of Utah Seismograph Stations and a research associate professor of geology and geophysics and the lead author of the study, said in a statement. "No one was killed, and yet now we have this rich dataset to learn more about landslides."

The researchers said that the landslide occurred in the form of two rock avalanches at 9:30 p.m. and 11:05 p.m., respectively. The slide is reported to have travelled at an average of nearly 70 mph and might have reached approximate speeds of at least 100 mph. The duration of each rock avalanche was 90 seconds.

The researchers used seismic scales to measure their magnitudes at 5.1 and 4.9, respectively.

They further added that the slides left behind deposits large enough to cover New York's Central Park and Salt Lake's Liberty Park .

Jeff Moore, co-author and an assistant professor of geology and geophysics, said the deposits were equivalent to the amount of material present in 21 of Egypt's great pyramids of Giza.

Although the landslide did not cause any injuries or fatalities, it did damage 14 haul trucks and three shovel trucks. Mine production was cut down to 50 percent and about 100 workers were let go.

Prior to the landslide at Kennecott's Bingham Canyon mine, there are records of huge human-caused landslides on other continents and during prehistoric times in North America. A landslide about five times larger than Bingham Canyon is reported to have occurred nearly 8,000 years ago at the mouth of Utah's Zion Canyon.

But the Bingham Canyon Mine slide "is probably the largest nonvolcanic landslide in modern North American history," Moore said.

The study has been published in the Geological Society of America magazine GSA Today.