About 63 trillion gallons of water have been lost to drought in the western United States, enough to blanket the region with 4 inches of water, according to a study published Thursday.
Researchers at the Scripps Institution of Oceanography at the University of California, San Diego, arrived at the conclusion by measuring the level of the earth's crust with a network of GPS stations that is normally used to predict earthquakes.
When water is lost because of a lack of rain and snow, the earth's crust rises. The sensors show that the earth's crust has risen an average of 4 millimeters in the western United States since last year and as much as 15 millimeters in the California mountains.
The earth's crust typically sags in the winter and spring, weighed down by water, and it rises during the dry season in summer and fall, said co-author Adrian Borsa. The authors removed those seasonal factors when analyzing about a decade of data from GPS stations within the National Science Foundation's Plate Boundary Observatory.