San Andreas fault reaches highest stress level in the last 1,000 years, new study suggests

A new study found that California's San Andreas Fault has reached its highest stress level in the last 1,000 years.

From the desert of Palm Springs to the San Francisco Bay Area, the 800-mile fault line snakes through much of California and has remained relatively calm in recent years. However, geologists warned that the pressure along the San Andreas has primed the state for a large earthquake scientists have referred to as "the big one."

"You got to remember, imminent to a geologist is like in the next century," renowned seismologist Dr. Lucy Jones said. 

Jones said the study unearthed a lot of new findings but fails to reveal everything.

"It doesn't tell us when the next earthquake's going to be," Jones said.

To understand the future, geologists looked at the past, compiling data from the last millennium and creating a snapshot of the historically high pressure. The relatively calm century has not provided a significant earthquake to ease the pent-up energy. 

"Unfortunately, in Southern California, you guys are plagued with a lot of different fault lines," said Harold Tobin, director of the University of Washington's Pacific Northwest Seismic Network. "Including the different parts of the San Andreas itself and other faults like the San Jacinto."

The faults intersect at the critical corridor of the Cajon Pass, which serves as a gateway through the entire state, meaning a potentially massive quake could stretch from one end of California to the next.

"There have been some earthquakes in the past that looked like they went the whole length, from south all the way north, through the Cajon Pass," Tobin said. "The stress is extra high on both sides of that right now, increasing the chances that the next one could rip right through that area there and could be a larger earthquake overall."

Called a double-fault rupture, the seismic activity is much worse than a single-fault event. As a baseline, San Francisco's Loma Prieta earthquake in 1989 was a single-fault event that killed 63 people. 

"Communities recover from disasters because they are strong communities, because people are connected to each other," Jones said. 

Experts hope the study could serve as extra motivation to take the big one a little more seriously.

"We want to know our neighbors so we know how to help each other afterward," Jones said. 

Jones said that smaller earthquakes through the Cajon Pass would not release enough energy.