GPS measures western US drought, finds Earth rising

AFP
As the severe drought in the western US continues, a field goes unplanted in Firebaugh, California on August 21, 2014
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As the severe drought in the western US continues, a field goes unplanted in Firebaugh, California on August 21, 2014 (AFP Photo/Justin Sullivan)

Washington (AFP) - Scientists using GPS technology to study the extent of the western US drought said Thursday the water shortage is causing parts of the Earth's crust to rise.

Some 62 trillion gallons -- equivalent to a six-inch (15-centimeter) layer of water -- have been lost since 2013, causing a slight upward lift across the region, according to the study in the journal Science.

The "uplift" effect equals some 15 millimeters (more than half an inch) in California's mountains and around four millimeters (0.16 of an inch) across the west.

The study was conducted by scientists at Scripps Institution of Oceanography at the University of California, San Diego.

Researchers found that precise GPS stations within the National Science Foundation's Plate Boundary Observatory and beyond had moved upward in recent years, coinciding with the current drought.

The study said the rise is not likely to increase the risk of earthquakes since it has "virtually no effect on the San Andreas fault."

Scripps researcher Dan Cayan said the technique could be used to measure changes in fresh water stocks across the globe.

"This technique can be used to study changes in fresh water stocks in other regions around the world, if they have a network of GPS sensors," said Cayan.

A NASA study out last month found the drought posed a major threat to underground water resources and the regional water supply.

Since 2000, seven western states -- including Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming -- have seen the driest 14-year period in a century.

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