Earthquake experts have called for Bay Area residents to prepare for the next big temblor.
But a group of scientists are now warning of the possibility of multiple large earthquakes that may hit the region. The scientists analyzed data from the past 400 years and believe they have identified a pattern.
"What stands out is this cluster of large earthquakes -- 6.6 to 7.8," said David Schwartz, a USGS earthquake geologist.
Schwartz said between 1690 and 1776 many large earthquakes shook the region and relieved built up stress. He and other scientists believe the pattern will repeat.
"We have several big ones in front of us rather than one single event like 1906," Schwartz said, referring to the magnitude 7.9 quake -- the last big release for the area.
Schwartz said the new theory complicates current plans for preparedness and recovery.
"If you have an earthquake and then years later you have another large earthquake seven years after that, it changes the dynamic," he said. "How do you prepare? What does it do to the economy?"