2 fault lines under San Francisco Bay connected, could produce major quake, study says

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SAN FRANCISCO (KTVU) -- The United States Geological Survey has found a missing link between two faults underneath the San Francisco Bay, a discovery that suggests an earthquake on the fault zone could be catastrophic for the region.

A team of USGS geologists have published new findings in the Science Advances journal, which suggest that if a quake on the connected Rodgers Creek and Hayward faults were to happen, the energy from the trembler could be five times greater than the devastating Loma Prieta quake of 1989.

In that quake 27 years ago, over 50 people were killed, portions of the Bay Bridge collapsed and several structures were destroyed before the shaking ended.

Scientists had thought previously that there was a 3-4 mile gap between the Rodgers Creek and Hayward fault zones. But the new data dispels that line of thinking.

"A direct link enables simultaneous rupture of the Hayward and Rodgers Creek faults," the researchers wrote. "A scenario that could result in a major earthquake that would cause extensive damage and loss of life with global economic impact."

Over 2 million residents live along the fault and David Ponce, a geologist with the group, told Popular Mechanics magazine that major transportation, gas, water and electrical lines traverse the fault zone. 

"So when it goes, it's going to be absolutely disastrous," he told the publication.

Researchers have been stymied by mud underneath the bay. But using a sound wave tool, geologists were able to track the pattern of the rocks underneath the bay and the evidence they found revealed the connection between the two fault zones.

The team suggested that Bay Area residents make sure they have a food, supplies and water to last several days after a major quake. Residents were also urged to have their homes bolted to its foundation.

KTVU reporter Alyana Gomez contributed to this report.