Under a statewide earthquake alert system, San Diegans would be warned approximately 20 seconds before the shaking began of a large earthquake on the southern San Andreas Fault. On the much closer San Jacinto fault, an early warning could mean just 5 to 10 seconds, but enough time for people to take cover, and to save lives.
The early warning technology was designed with the help of researchers from Scripps Institution of Oceanography, who have worked for decades on earthquake sensors.
"The data shows up right here, so that tells us we have the data, we can process it and pass on that information right as it arrives," said Research Seismologist Frank Vernon, as he explained the real time information streaming onto large monitors in his La Jolla office.
Vernon is a leader of seismology sensors, an instrument that detects initial seismic waves after a fault ruptures and assesses the strength and direction of secondary waves before the shaking begins.
"Seismology tends to measure dynamic motion, so it measures how fast things shake and what the accelerations are," said Vernon.
The same seismic instrument alerted millions of people in Japan up to a minute before the massive 9.0 earthquake on March 11, 2011. But it took 20 minutes to accurately determine the quake's magnitude, which was initially underestimated, said Vernon.
That’s where Research Geodesist Yehuda Bock and his team come in. They’ve led the development of GPS sensors, which directly measure ground motion and can rapidly determine a quake’s magnitude.
"We use GPS observations to measure small movements of the ground, we measure static displacements, we measure permanent deformation," Bock explained.
Bock and Vernon have placed dozens of their sensors along California’s active faults. Although Vernon's focus is on the San Jacinto Fault, he said he has sensor stations located throughout Southern California.
"We operate 30 stations in the Riverside County and San Diego County spanning all the way out to San Clemente Island and over to the Salton Sea area near palm springs," said Vernon.
Bock's GPS network consists of hundreds of instruments along the San Andreas fault system, which includes San Jacinto, Elsinor and Imperial faults.
"We've placed stations to fully cover the different faults in Southern California," said Bock. "It’s important to not only be on the fault itself but also to measure deformation and movements of the earth away from the faults so you get a complete picture of how the stress is accumulating throughout the area."
Bock and Vernon are working to combine the two technologies to provide a more complete description of what occurs during an earthquake.
They hope the model will be used for California’s early earthquake warning system, which was ordered by Gov. Jerry Brown last week, and scheduled to be implemented by 2016.
"Yehuda and myself have spent a lot of time working in this region, and we have a very vested interest in making sure it gets done right in southern most California," said Vernon.
More complex than the technology could be training the public on how to respond to an earthquake warning with just a few seconds warning.
"I think the thing you start looking at in the long-term is the machine-to-machine interactions that you can set up in the communications infrastructures to start doing automatic shutdowns, or specific services or utilities that might have either strong economic or public safety issues," said Vernon.
"Stopping elevators, alerting surgeons who are in the middle of operations, turning off gas lines, electricity and starting up generators — things like that that can be done in real time," added Bock.
California's early warning system will require upgrading current monitoring stations and adding hundreds of sensors to create a full-scale network. The system is expected to cost approximately $80 million to build and run during the first five years.
