Officials say the findings of a new study should remind people to be ready for "The Big One."
Scientists have discovered more big earthquakes -- meaning more than a 6.5-magnitude on the Richter Scale -- have hit California's San Andreas Fault than previously thought.
"This is more of a wakeup call in the sense that previously we thought these large ones occurred every 200 to 400 years, but it looks like they actually occurred more frequently," said Sinan Akciz, UC Irvine's earthquake study lead author.
UC Irvine scientists dug trenches across the San Andreas Fault in the Carrizo Plain area, about 100 miles northwest of Los Angeles. Using radiocarbon dating, researchers found evidence of six big quakes in the past 700 years. The last major one hit more than 150 years ago.
The new research shows the big ones happened without waiting 200 years, as was previously thought.
"The time period between individual earthquakes ranges between 45 years to 145 years," said Akciz.
When "the big one" will hit is still anyone's guess, but the aftermath of large quakes in Haiti and Chile show how overwhelming the devastation can be.
A computer simulation shows how a 8.0-magnitude earthquake rolling across Southern California could affect about 25 million people, with the shaking felt as far away as Yuma, Arizona.
Scientists hope their research will get people who have grown complacent to wake up and take the time to prepare.
To be prepared, the experts always say to make sure you have enough food and water to last at least three days. Talk with your family to figure out a plan in case something happens.