(NaturalNews) With about 60 percent of the state now limping through the worst categorical level of drought on record, California faces an unprecedented water crisis that, besides triggering shortages, stands to greatly influence the availability of fresh produce nationwide. And as far as its own residents and the residents of nearby states are concerned, there is an additional threat also waiting in the wings: the increased likelihood of earthquakes.
A new study published in the journal Nature raises some serious questions about the stability of California now that underground aquifers are plunging to record lows. All throughout the Central Valley, which grows most of the nation's lettuce, almonds and other produce, more water is being pumped out of the ground than is being put back in, a phenomenon that researchers say is causing the ground to shift.
According to a team of geologists led by Colin B. Amos from Western Washington University, the subterranean landscape beneath the earth, also known as the lithosphere, is literally separating from the land on top throughout California. The California Coast Ranges, the Tehachapi Mountains, and the southern Sierra Nevada, says TakePart's Chris Clarke, are rising by as much as three millimeters per year, or roughly an inch every 10 years.
A series of 500 GPS recorders carefully placed throughout the Central Valley and its surrounding mountains revealed that the water table throughout the area is rapidly dwindling. This means that the 176 billion-ton water load that normally holds down the lithosphere is becoming increasingly lighter, resulting in a land separation that, historically speaking, has made the ground more prone to seismic activity.
"Groundwater pumping unburdens the lithosphere," said William Hammond, a geologist at the University of Nevada and co-author of the study, as quoted by TakePart. "When you pump that much groundwater, the load gets taken away and the landscape essentially bounces up. The Sierra Nevada is rising more quickly as a result of groundwater pumping in the Great Valley."
2011 earthquake in Spain caused by water overdrafts, say scientists
Back in 2011, a 5.2-magnitude earthquake that rocked Lorca, Spain, killing 10 people and causing extensive infrastructure damage, was found to have been caused by the overdraft of water from local aquifers. A cohort of researchers determined that, based on the fault slip pattern and movement of land at the surface, changes in aquifer volumes were the most likely cause of the quake.
"The area of fault slip correlates well with the pattern of positive Coulomb stress change that we calculate to result from the extraction of groundwater in a nearby basin aquifer," wrote the authors of a study published in the journal Nature Geoscience. "Our results imply that anthropogenic activities could influence how and when earthquakes occur."
In the Central Valley, a similar phenomenon has been documented in relation to when the most water is drawn from underground aquifers to nourish crops. In the late summer and early fall, according to geologists, the Parkfield section of the infamous San Andreas Fault system typically experiences increased seismic activity exceeding 1.25 magnitude or higher, which is also the time when the most water is drawn.
"That seasonal change means loading and unloading on the lithosphere," added Hammond. "The earth flexes up and down, and small earthquakes seem to respond to that."