A new early warning system is being developed in California to give residents more time to react to imminent seismic events like the 1989 Loma Prieta earthquake, which collapsed the two-level Cypress Street Viaduct of Interstate 880 in West Oakland and damaged the San Francisco–Oakland Bay Bridge. Wikimedia Commons/sanbeji/Joe Lewis
Last month, California Governor Edmund G. Brown, Jr., signed into law Senate Bill 135, which calls for the development of a statewide seismic early warning system.
October 29, 2013—Seismic early warning systems can provide people with valuable seconds to prepare for an arriving earthquake. These systems give everyone a chance to seek safe shelter, give train operators time to begin stopping trains, and give factory supervisors the opportunity to stop machinery that could be irreparably damaged or cause dangerous spills in an earthquake. Last month, California Governor Edmund G. Brown, Jr., signed into law SB 135, a senate bill calling for the creation of a statewide earthquake early warning system.
Introduced by Senator Alex Padilla (D-Pacoima), the law requires the California Governor’s Office of Emergency Services to develop a comprehensive statewide earthquake early warning system, to develop standards and review methods for the system, and to identify funding for the system.
The law notes that a number of agencies and research bodies—including the California Governor’s Office of Emergency Services, the California Institute of Technology in Pasadena, the California Geological Survey, the University of California Berkeley, and the United States Geological Survey—have already been conducting seismic early warning research and development as part of the California Integrated Seismic Network, so the development of a statewide comprehensive system can build upon this work.
Early warning systems work by identifying seismic waves as they travel outward from an earthquake’s epicenter. “It’s not earthquake prediction, it’s an earthquake forecast,” explains Jennifer Strauss, Ph.D., the science liaison and external relations officer for the University of California Berkeley Seismological Laboratory. Researchers in the laboratory have been key participants in developing an early warning system for California.
Work by the California Integrated Seismic Network has involved creating algorithms that can rapidly interpret real-time earthquake data in California and broadcast warnings of an arriving earthquake to distant locations before the earthquake waves reach them. In an earthquake, “there are two main wave fronts that come out with the radiated energy,” Strauss says. “There is the primary wave—the P wave—and the secondary wave—the S wave. The P wave travels at twice the speed of the S wave, so it is basically outrunning it, and if you set up sensors around faults and a sensor records the P wave, you can do some analysis on what that P wave looks like—its characteristics—and be able to say something about the S wave that is coming. And the S wave is the one that does the damage.”
Although research and development of the algorithms necessary for an early warning system in California have been ongoing for the last decade, according to Strauss, what has been missing until relatively recently is the ability to analyze this information quickly. “A repeat of the Loma Prieta earthquake [in 1989] would give San Francisco and Oakland about 24 seconds of early warning, based on the system we have right now,” she says. “But if your algorithms take 30 seconds to run, because you haven’t developed the sort of computer and telemetry speed [you need], then that doesn’t really help.”
Early warning systems already exist elsewhere in the world, according to Strauss: Mexico implemented one after the devastating magnitude 8.0 Mexico City earthquake in 1985 and Japan developed one after the magnitude 6.9 Kobe earthquake in 1995. However, these are subduction zone earthquakes, which involve different sorts of algorithms than would work in California, she points out.
Now that the algorithms for California have been developed, the detection systems can be expanded with the placement of additional seismometers around the state.
Methods of broadcasting notice of an impending earthquake to the public also need to be developed, Strauss says. The challenge will be “identifying methods that can reach the most amount of people that also have the speed necessary to make the alert worthwhile,” she says. A second hurdle will be educating the public so they know how to respond when the alert arrives. “If you start blaring sirens or giving people noises on their cell phone or alerting them to the TV, if you don’t have a public who knows what that means, then they’re not going to be able to act appropriately to protect themselves,” she says. “But it’s just like fire drills: people do fire drills and they don’t really think about it anymore, it’s just sort of something that you do. So we just need to add earthquake drills to that.”
The law gives the California Governor’s Office of Emergency Services a deadline of January 1, 2016, to identify funding to develop the seismic early warning system. At that point, the law will be repealed unless another statute is passed extending the date.
Richard Allen, the director of the University of California Berkeley Seismological Laboratory, and his colleagues estimate that $80 million will be necessary over the next five years to deploy additional seismic sensors around the state and perfect the system, according to a press release issued by the University of California Berkeley. Operating the system will cost $12 million annually.
“In the grand scheme of what the state and other entities have to pay for, this is not a huge endeavor,” Strauss notes. “I’m just hopeful that we’ll get everybody together and talking on the same page and that we don’t have to have this price tag hanging over it that sort of makes or breaks the system.”
The California Governor’s Office of Emergency Services, tasked with oversight of bringing the seismic early warning system online, agrees with the need for the system: “The signing of Senate Bill 135 by Governor Brown is a critical step forward in our efforts to provide Californians with enough warning that an earthquake capable of producing intense ground shaking has begun,” said Mark Ghilarducci, the director of the California Governor’s Office of Emergency Services and the homeland security advisor to the governor, in a statement released by his office on the day the bill was signed.
“On the road toward a comprehensive earthquake early warning system, we will face some challenges,” said Ghilarducci. “Fortunately the California Integrated Seismic Network provides us with the foundation for the system we envision…. [W]e are committed to doing all we can to make this a reality.”