Associated Press
LOS ANGELES — Changes in groundwater levels cause Los Angeles to rise and fall by more than 4 inches every year, complicating the work of seismologists studying the risk of earthquakes.
The human pumping and recharging of drinking water cause the spongelike ground to breathe with a heaving regularity that scientists have measured at the surface and from space.
To the chagrin of earthquake scientists, much of that motion is being recorded by instruments designed to measure the far more subtle movement of the Earth’s tectonic plates.
While the groundwater effect has been detected elsewhere, including Las Vegas and San Jose, Calif., the magnitude and extent of the motion seen in greater Los Angeles is unprecedented, said Gerald Bawden, a research geophysicist.
"The Los Angeles basin is like an adult human breathing," Bawden said.
The findings are reported in today’s issue of the journal Nature.
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