Large earthquake the size of Loma Prieta possible in Silicon Valley

STANFORD, Calif. - Scientists at Stanford warned of a large earthquake possibly brewing in Silicon Valley.

The new study found that two faults, known together as Foothill Thrust Belt, could produce a quake as big as the Loma Prieta that rattled the Bay Area in 1989.

They said the 6.9 magnitude shake could happen every 250-300 years along this belt.

ALSO: California earthquake alerts: how to get notified before a quake

While it's a cautionary warning, seismologists admit they have no way of predicting exactly when a large quake could strike.

California uses science, state-of-the-art ground motion monitoring, and new and existing alerting methods to deliver warnings to residents' cell phones before the strongest shaking arrives.

The state's earthquake warning system was activated swiftly a few weeks ago when a 4.4 magnitude temblor hit Santa Rosa.