Extracting water for human activities is increasing the number of small earthquakes being triggered in California.
A new study suggests that the heavy use of ground water for pumping and irrigation is causing mountains to lift and valleys to subside.
The scientists say this depletion of the water is increasing seismic activity along the San Andreas fault.
They worry that over time this will hasten the occurrence of large quakes.
The report has been published in the journal Nature.
The San Andreas fault runs for almost 1,300km through the western part of California and marks part of the boundary between the Pacific and North American tectonic plates.
Seismologists have mainly focussed on the movements of these plates as the critical factors in the build up of stress that can lead to large earthquakes, such as the one that destroyed San Francisco in 1906.
This paper looks at another factor – the impacts of humans on the Earth's surface.
The researchers have used the well developed GPS system in the western US to analyse small lifts and dips in the topography of the San Joaquin valley.
San Joaquin is part of California's central valley, one of the most productive farm regions in the US. That productivity is based on access to ground water, extracted and pumped to irrigate crops.
So great is the demand that scientists estimate twice as much water is being consumed as is being returned through rain and snow.
All this extraction is having a significant impact on the shape of the Earth. The floors of the valleys are subsiding, the researchers found, while the surrounding mountains are on the rise.
"We are removing a weight from the Earth's crust and it is responding by flexing upwards and literally moving mountains," lead author Dr Colin Amos told BBC News.
Written By: Matt McGrath
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