Water is heavy — ask anyone who screwed up the Ice Bucket Challenge. And California and the rest of the West Coast have precious little of it. The water is so depleted, it's not weighing down the earth's surface — and geologists have measured a rise of up to 15 millimeters at GPS stations across the West.
Poring over data from the GPS stations that monitor earthquake activity throughout California, researchers at the Scripps Institution of Oceanography at U.C. San Diego found that the land across the west has experienced an average "uplift" of four millimeters, or 0.15 inches, in the past eighteen months. Stations located in California's mountains show the greatest uplift, topping out at 15 millimeters or just over half an inch.
You and I might think of the ground beneath our feet as rigid and non-pliable, but that's not really the case. "Think of the Earth as a big rubber ball," Scripps geophysics professor Duncan Agnew explained to Popular Science. "It's made of material that is elastic, and if you push on it, it goes in a little bit. If that push is taken away, by water evaporating, there's less weight on that part of the earth, and it goes up."
Just how massive is that water loss? In a paper published this week in Science, the team estimates the deficit at nearly 240 gigatons, or 63 trillion gallons of water. That much water spread across the entire western United States would run four inches deep.
If there's one piece of good news here, it's that the uplift of the tectonic plates in the drought zone shouldn't change the likelihood of earthquakes or other seismic events. "This will change the stress on faults, but by an amount that's really small," Agnew told Popular Science.