Researchers monitoring small ground motions along faults in Southern California
Map of the Los Angeles area shows land subsidence in summer of 1999. The largest drop, about 5.4 centimeters,
was near downtown Santa Ana (arrow). The smallest drops were in the north and are shown in blue and violet. Bawden
ended up detecting an altogether different phenomenon: the rise and fall of the
ground as local governments pump billions of gallons of water into and out of the
region’s aquifers.
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