Science briefs: Utah avalanche was the largest in modern history

  • Updated: January 11, 2014 - 4:19 PM

the Largest avalanche in modern history

The avalanche near Salt Lake City last year that carried enough rock, dirt and debris to bury New York’s Central Park under 66 feet of rubble was North America’s largest such disaster in modern history, University of Utah scientists said.

The April 2013 rockslide sent 165 million tons of debris into a nearly mile-deep pit where it cracked bedrock and triggered unprecedented earthquakes, the researchers said in a study published in the Geological Society of America’s magazine, GSA Today.

“We don’t know of any case until now where landslides have been shown to trigger earthquakes,” said Jeff Moore, assistant professor of geology and geophysics.

There were no injuries as the slide temporarily shut down a copper mine, burying 14 giant haul trucks and leading to a series of layoffs and buyouts at Kennecott Utah Copper Corp. The slides fell as fast as 100 mph and with such force that they registered as magnitude-5 earthquakes and then triggered 16 smaller quakes where the bedrock cracked, Moore said.

yes, we’ve become weather wimps

As the world warms, the United States is getting fewer bitter cold spells like last week’s. So when a deep freeze strikes, it seems more unprecedented than it really is.

An Associated Press analysis of daily national winter temperature — averaged into one figure for the Lower 48 states — shows that since 1900, cold extremes like this week’s happen about once every four years.

Until recently.

Government meteorologist Greg Carbin created a database of the winter daily national temperature average going back to 1900. And Monday was the first time since 1979 that the national average temperature dropped below 18 degrees.

In the past 115 years, there have been 58 days when the national average temperature dropped below 18. Carbin said those occurrences often happen in periods that last several days so it makes more sense to talk about cold outbreaks instead of cold days. There have been 27 distinct cold snaps.

Between 1970 and 1989, a dozen such events occurred, but there were only two in the 1990s and then none until Monday.

“These types of events have actually become more infrequent than they were in the past,” said Carbin, who works at the Storm Prediction Center in Norman, Okla. “This is why there was such a big buzz because people have such short memories.”

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