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Study: Sierra range adds about 1-2 millimeters in elevation a year

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POSTED May 6, 2012 9:36 p.m.

TRUCKEE (AP) — The Sierra Nevada range continues to grow about one-half inch in elevation every 10 years, and scientists say new technology that allows them to detect the relatively fast rate of uplift in the crust from space is helping shed new light on the origin of the mountains.

Researchers at the University of Nevada's Geodetic Laboratory in Reno and University of Glasgow in the United Kingdom say they've recorded annual elevation increases between 1 and 2 millimeters for more than 10 years along the entire 400-mile-long range that straddles the Nevada-California line.

They say a combination of GPS data and space-based radar has provided them with unprecedented accuracy in measuring the uplift of the crust compared to Earth's center of mass and to relatively stable eastern Nevada.

"The exciting thing is we can watch the range growing in real time," said Bill Hammond, the lead researcher of the multi-year project at the University of Nevada.

"Using data back to before 2000 we can see it with accuracy better than 1 millimeter per year. Perhaps even more amazing is that these minuscule changes are measured using satellites in space."

The research was funded by the National Science Foundation and NASA, along with the United Kingdom's Natural Environment Research Council.

Zhenhong Li contributed from the University of Glasgow in Scotland, where he is a senior lecturer at the School of Geographical and Earth Sciences' Centre for the Observation and Modeling of Earthquakes, Volcanoes and Tectonics.

Hammond's team in Reno included three research professors at the Nevada Bureau of Mines and Seismological Laboratory — Geoffrey Blewitt, Peter Plag and Corne Kreemer.

Hammond said the new findings to be published in the journal Geology in July may help resolve an active debate regarding the age of the modern Sierra in California and Nevada.

The Sierra Nevada stretches from 10,000-foot peaks in the north around Lake Tahoe to the highest peak in the continental U.S. 400 miles south — Mt. Whitney at about 14,500 feet.

"Combined with more GPS stations, and more radar data, detecting motions in the Earth is becoming more precise and ubiquitous," he said. "We can see the steady and constant motion of the Sierra in addition to episodic events such as earthquakes."

Hammond said the history of the Sierra's elevation is complex and the uplift process "fairly unique on Earth." It exhibits features of both ancient elevation — as old as 40 million years — and relatively young elevation dating to less than 3 million years ago.

"Our data indicate that uplift is ... active and could have generated the entire range in less than 3 million years, which is young compared to estimates based on some other techniques," he said. "It basically means that the latest pulse of uplift is still ongoing."

 

 

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