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"Moving Mountains" -- The Discovery Files

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Scientists at the University of Nevada, Reno have shown that draining of the aquifer for agricultural irrigation in California's Central Valley results in upward flexing of the earth's surface and the surrounding mountains due to the loss of mass within the valley.

Credit: NSF/Karson Productions

Audio Transcript:

(Sound effect: rumble) Uplifting.

I'm Bob Karson with the discovery files--new advances in science and engineering from the National Science Foundation.

If you've re-visited the Sierra Nevadas and thought they seemed a little taller, you're very perceptive. The mountain range is rising about the thickness of a dime each year. Doesn't seem like much, but in geological time, it's quite fast, a cumulative rise of about six inches since the mid 1800's. A study led by the University of Nevada, Reno looks at the potential causes.

Seems one may be human activity, specifically, the draining of the aquifer in California's Central Valley for agricultural irrigation. You see, all that water weighs a lot. Remove the water, and you remove the weight causing the earth to flex upward. Mountains rise as well as the valley.

How much water's been drained? The researchers say in the past 150 years, enough to cover the entire state of California with 14 inches. (Sound effect: light waves) (Sound effect: surfer dude: "whoa, gnarly")

The data for the study was gathered between 2007 and 2010 from California and Nevada GPS measurements. The info was processed at the Nevada Geodetic Lab, which measures the shape of the earth every day, using GPS data from some 12,000 stations around the world and in space.

Guess you could say they gave us a 'mountain' of evidence.

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