A section of the San Andreas Fault in California is overdue for a major earthquake that could reach 8.1 magnitude, researchers say.

If or when it happens, seismologists say, the earthquake could run 340 miles from Monterey in central California south to the Salton Sea, the Los Angeles Times reported.

Experts previously believed a major section of the fault 100 miles northwest of Los Angeles would remain dormant for at least another century.

But new studies suggest even that section of the fault is overdue for the "Big One," seismologist Lucy Jones said.

"All of it has plenty enough stress for it to be ready to go," Jones said. "The biggest implication of [the report] is that it increases the likelihood that when we do have a big earthquake, it will grow into the 'wall-to-wall' rupture."

The "walls" are the boundaries of the southern San Andreas, which begin at the Salton Sea and end in the town of Parkfield in Monterey County.

Seismologists generally consider the southern San Andreas Fault as a single segment because it all behaves the same -- it rarely rumbles, but when awakened, the shaking can be devastating.

The San Andreas has long been considered one of the most dangerous faults in Southern California because of its length.

Not only do longer faults produce bigger quakes, they emit a type of shaking energy that can travel longer distances.

"So a much larger area is affected by a really large earthquake," Jones said.