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AMERICAN CANYON – Sensors relayed a message to the 911 Emergency Communications Center on Turk Street in San Francisco immediately after the earth slippage seven miles deep, causing the south Napa earthquake.

“Earthquake, earthquake, light shaking expected in nine seconds,” an electronic voice said.

With that “brace yourself” warning, the high-tech response to the Aug. 24 South Napa earthquake began. This Digital Age disaster in its aftermath saw everything from drones to social media to a National Aeronautics and Space Administration radar airplane playing roles in recovery and research.

“I think this has become one of the most well-documented earthquakes we have seen in the last several decades,” said Steve Mahin, director of the Pacific Earthquake Engineering Research Center.

Mahin and other spoke at a meeting of the state Alfred E. Alquist Seismic Safety Commission on Wednesday at the DoubleTree Hilton Hotel and Spa in American Canyon. The state commission routinely does post-mortems on earthquakes of this size to look for lessons learned.

The earthquake provided a chance for the state’s nascent Shake Alert early warning system to show what it can do. Agencies such as BART received a few seconds warning of the earthquake, which in BART’s case can provide a chance to slow down its trains, officials said.

Napa received not even a few seconds warning, being so close to the epicenter as to be in the warning system’s “blind zone” of about nine miles. Richard Allen, director of the UC, Berkeley Seismological Lab, said work is being done to reduce the size of this zone.

“This is a demonstration system,” Allen told the commission.

Another high-tech response would have been noticeable to people on local streets. “We have a little drone we’ve been flying around Napa, probably to the annoyance of residents,” Mahin told the commission.

But that drone has been useful, swooping down on earthquake-damaged buildings with a camera to transmit views from above.

“You don’t want to go on the roof of a building that’s on the verge of collapse,” Mahin said.

Mahin noted that science has provided better mapping of the West Napa Fault that caused the earthquake than was available even a few years ago. That can help cities stop buildings from being constructed directly on top of the fault and interrelated faults.

He showed a computer program that can matched faults in the region with specific buildings. Commissioners laughed when Mahin announced that the hotel they were inside was located within 150 feet of a fault.

Susan Owen told the commission about the earthquake response by NASA’s Jet Propulsion Laboratory.

The agency worked with global positioning data and images taken from satellite-based radar and from a NASA radar airplane. This data, when compared to previous images of the area, gave scientists information on how the surface of the earth had changed, down to less than a half-inch.

But this went beyond knowledge for knowledge’s sake. Owen said the agency relayed the results of its findings to field teams looking for surface ruptures that can affect such things as water lines.

The radar airplane looked for damage to levees in the San Pablo Bay area and found them stable, Owen said. It can locate hard-to-see damage in buildings – with limitations.

“It doesn’t necessarily see when wine barrels have fallen and broken inside the building,” Owen said.

Local governments also turned to high-tech tools, officials told the commission. For example, firefighters coming to Napa from other areas on Aug. 24 used computer tablets to find their way around an unfamiliar area.

Napa Mayor Jill Techel told the commission how the city used Facebook to communicate with citizens in the wake of the earthquake.

She talked about how smart phones played a role in the minutes and hours after the 3:20 a.m. earthquake. Citizens could use them for flashlights and to find out that Napa had been hit the hardest by the quake and wasn’t on the fringes of a Big One that had done even more damage to San Francisco.

“I really think that kind of technology helps people recover more quickly, because they have more information,” Techel said.

Techel and county Board of Supervisors Chairman Mark Luce told the commission about the local earthquake response efforts and the help that Napa County received from emergency responders all over the region.

Luce also talked about the response of citizens. When merchandise from an earthquake-damaged store ended up on the street, people rather than looting helped put the merchandise back inside the store, he said.

Commissioner Emir Macari said that the south Napa earthquake could be used as a case study in professional literature about how an earthquake response is done.

But there were some bumps. At least one house that should have been red-tagged for no use because of earthquake damage instead was green-tagged, said Charles Rabamad, assistant director of the state Office of Emergency Services Recovery Section.

“This is something we really need to look into, because it shouldn’t have happened,” Rabamad said.

Several local officials expressed dismay about the ongoing delay in receiving a federal disaster declaration that would bring financial assistance for homeowners and businesses. The Sept. 11 disaster declaration applied only to government and certain nonprofit agencies.

After the 2000 earthquake, Napa received such disaster status immediately, even though that earthquake was a quarter of the strength of the Aug. 24 earthquake and did a quarter of the damage, Luce said.

“That’s critical to recovery,” Luce said.

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