LOS ANGELES, Aug. 20 (Xinhua) -- Earthquakes on the southern San Andreas fault have been much more frequent than previously thought, indicating that California is over due for a huge temblor, a new study suggests.
Many seismologists believe that a major rupture is possible because the San Andreas fault has been in a quiet period, said the study published on Friday in the journal Geology.
In the study, researchers at University of California, Irvine ( UCI) used charcoal samples to look for earthquake activity going back centuries.
"What we know is for the last 700 years, earthquakes on the southern San Andreas fault have been much more frequent than everyone thought," UCI researcher Sinan Akciz said in a statement. "Data presented here contradict previously published reports."
The study came after scientists spent years studying the geology of the Carrizo Plain area of the San Andreas, which is about 100 miles (160 kilometers) northwest of Los Angeles.
The last massive earthquake on that part of the fault occurred in 1857. But researchers found that earthquakes have occurred as often as every 45 to 144 years.
That would make the region overdue for the type of catastrophic quake often referred to as "The Big One," the researchers said.