California remains one of the most earthquake-prone regions in the United States, according to a 2017 U.S. Geological Survey, or USGS, forecast that shows the impact of both induced and natural earthquakes.
The forecast highlights the nation’s most vulnerable regions and provides safety information for those at most risk. Earthquakes typically have recurrence times around 100 to 200 years. Under this assumption, the USGS can perform 30-year probability studies to calculate the chance that an earthquake occurs in a specific area within the next 30 years in addition to the hazard lists, according to Mark Petersen, leader of the USGS National Seismic Hazard Mapping project.
“The probability is pretty likely that you’ll have one somewhere in the San Andreas Fault system — Hayward, Rodgers Creek across the Bay too — several different earthquakes that could rupture in that area,” Petersen said. “There’s a 70 percent chance of a magnitude 6.8 earthquake hitting the Bay Area in the next 30 years.”
Induced earthquakes are triggered by human activity, primarily disposal of wastewater by injection into underground wells. The fluid buildup causes changes in pressure that weaken a fault over time.
According to the USGS forecast, these induced earthquakes have been observed in California, but don’t significantly change the hazard level, which is already high due to frequent natural earthquakes. The sheer number of faults in California that produce natural earthquakes overwhelm the effects of induced earthquakes, according to Petersen.
The Hayward Fault, a member of the San Andreas Fault system that runs through California, extends along the foot of the East Bay hills in Berkeley and underneath Memorial Stadium. The last major earthquake along the Hayward fault occurred in 1868. The 1868 quake had a 6.8 magnitude and caused significant damage to the Bay Area.
UC Berkeley has already taken measures in preparation for the big quake. According to the campus’s SAFER program’s website, a program implemented in 1997 to improve structurally vulnerable buildings on campus, buildings such as Barrows Hall, Haas Pavilion, Doe Library and Latimer Hall were retrofitted or made more structurally resistant to seismic activity. These improvements have reduced safety risks for students and faculty by 50 percent.
“The need to be prepared for earthquakes here in Berkeley has never been greater,” said Grace Kang, spokesperson for Pacific Earthquake Engineering Research Center, or PEER.
PEER is a research center headquartered at UC Berkeley that consists of five UC schools and five non-UC schools along the west coast. Its primary research objective is to develop tools that evaluate the impact of earthquakes on the community and economy, according to the PEER website.
“People need to have earthquake kits ready,” said Kang. “They must learn how to duck, take cover and hold on.”
Contact Carina Zhao at [email protected].