Forget San Andreas, Next Earthquake Could Topple San Francisco, Two Bay Area Fault Lines Connected

Scientists have long feared a large San Andreas earthquake could cause massive damage to California, but now new evidence linking two different San Francisco fault lines together suggest a Bay Area temblor could be worse.

A team of scientists from the United States Geological Survey published a new study in Science Advances on Wednesday that links the Hayward and Rodgers Creek fault lines and increases the chance for a major earthquake.

If both faults were to break simultaneously, a chance that increases because they’re connected to each other, the resulting earthquake could measure a magnitude 7.4, lead researcher Janet Watt told Popular Mechanics.

“The longer a fault stretches, the bigger the earthquake it can produce and here we’ve just doubled the length of this fault.”

The resulting quake would be five times larger than the Loma Prieta earthquake in 1989 that killed more than 60 people, injured thousands, caused billions of dollars in damages, and collapsed part of the San Francisco Bay Bridge.

[Image by Cameron Spencer/Getty Images]
[Image by Cameron Spencer/Getty Images]

Seismologists have long feared a Hayward Fault rupture because it runs under densely populated San Francisco Bay Area neighborhoods and now seismologists say there’s a 32 percent chance of a rupture in the next 30 years. There hasn’t been a major quake along the Hayward Fault in more than 140 years so it’s primed and ready to go.

The now connected Rodger Creek and Hayward fault lines run for 115 miles from wine country in the north through the east bay to Oakland and reach all the way to San Jose, researcher David Ponce told Popular Mechanics.

“You have to understand that there are over 2.4 million people living right along this fault, and the population of this whole area is around 7.5 million. It also turns out that major transportation, gas, water and electrical lines cross this fault. So when it goes, it’s going to be absolutely disastrous.”

Researchers used a specially designed seismic profiler to scan the seafloor under the Bay for anomalies that appear near fault lines along with a high-frequency imager that allowed them to “see” the fault lines with radar and sonar.

null

The underwater survey allowed researchers to discover a previously unknown part of the Hayward Fault that connects to the Rodgers Creek Fault, Berkeley geophysicist Roland Burgmann told YahooNews.

“Having a continuous fault does certainly make it easier for an earthquake rupture coming from either the north or the south to continue straight through.”

Both the fault lines run parallel to the San Andreas Fault which has had its own shaking issues recently. In Southern California earlier this month, seismologists recorded more than 200 small earthquakes occurring along the San Andreas Fault near the Salton Sea.

The swarm of tremors, recorded over a week’s time, prompted earthquake warnings for Ventura, San Diego, San Bernardino, Riverside, Orange, Los Angeles, Kern, and Imperial counties.

Researchers agree that more seismologist studies increase preparation for strong earthquakes and could prevent loss of life and property, Watt told Live Science.

“We always need reminders that earthquakes occur, because they can happen so infrequently and we need to be prepared for something stronger than the Loma Prieta.”

[Image by David McNew/Getty Images]
[Image by David McNew/Getty Images]

To help preserve life and protect California property, Governor Jerry Brown signed a bill to help kick-start a statewide earthquake monitoring system that could give residents up to a one-minute warning.

That might not sound like a long time, but it would be sufficient to slow down fast moving trains, give time for students to duck under their desks, and help first responders evacuate people

Japan, Taiwan, and Mexico already have early warning systems using technology developed in California.

Officials remind California residents that they should be ready for a strong earthquake at any time; always have supplies of food and water on hand as well as an evacuation plan and meeting point.

The next earthquake drill, the Great American Shakeout, is scheduled for Thursday, Oct. 20.

[Featured Image by Justin Sullivan/Getty Images]