Large-scale use of underground water resources in California could spur small earthquake in the area. Scientists deduced this after conducting a study the San Joaquin Valley which is heavily irrigated due to the region's agricultural activities. They said the activity of San Andreas Fault can be affected by water loss. Increase in the local population, growth in agricultural demands and the recurring drought are the likely cause of water depletion.

The more the depletion of that groundwater the more the chances of failure of that fault, said Paul Lundgren of NASA's Jet propulsion Laboratory.

They found the decrease in the water source in San Joaquin Valley is almost equal to the level of Lake Tahoe. The study of the surrounding land features of the valley has led the researchers to reach at the conclusion that lowland areas are likely to sink and mountains to rise because of the large-scale water loss.

Change of around 41 centimeters has been recorded in the height of the mountains. The water acts like a weight that pushes down the earth's crust, said Colin Amos, a geology professor at the Western Washington
University.

Amos explained that the forces responsible for clamping the fault together become weak because of the water loss. This will lead to more small earthquakes during dry periods of time.

"These are small earthquakes we're dealing with. During a large earthquake, the change in stress you'd see on a fault is much, much greater than the magnitude of stress changes we're calculating," he added referring to the surface changes", said Amos.

Lundgren is of the belief that the occurrence of small earthquakes is likely to encourage the development of a larger one. He said it is unclear how far that fault will go before the next large earthquake occurs.