Prototype Earthquake Early Warning System (Interview)

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Detailed Description

Retired seismologist David Oppenheimer reflects on the first prototype earthquake early warning system used during the 1989 Loma Prieta earthquake. Scientists deployed an analog system to notify first responders of impending earthquake activity as they worked on rescue efforts at the Cypress Viaduct collapse in Oakland, CA.
 

Details

Image Dimensions: 758 x 512

Date Taken:

Length: 00:02:21

Location Taken: CA, US

Video Credits

David Oppenheimer, Paul Laustsen, Susan Garcia
 

Transcript

After the earthquake the Cypress Structure collapsed. [The Cypress Structure is a two-tiered part of the Nimitz Freeway.] People were trapped in cars. And people were working on the structure trying to free people, dismantle the structure so it wouldn’t collapse and kill other people. And my colleagues Bill Bakun, and Grey Jensen, and John VanSchaack, and I’m probably leaving out others, realized that they could actually do what we now call “earthquake early warning.” They put a[n] analog piece of equipment near the epicenter of Loma Prieta. It sent its signal essentially at the speed of light to Menlo Park. A simple analog circuit said, “If I see this kind of amplitude I’m going to send a signal up to the Cypress Structure,” where we had some sort of annunciator . . . I forget what it was. And it would give people on the structure, I believe, on the order of 15 seconds of warning before a large earthquake. Large being magnitude M4.5 or something in that neighborhood. I’m a little rusty on all this. It turns out that while it worked. . . . First of all the earthquake, itself, was pretty devoid of large magnitude aftershocks. I believe there was only one magnitude 5? But even so, the interest in this prototype earthquake early warning system was to warn the workers that shaking was coming. There was no time for them to get off the structure with 15 seconds. But [what] they were afraid of was that the structure was becoming unstable and was about to collapse. So if they knew it was an earthquake [shaking the structure] that was to be expected. Shaking without an earthquake . . . ”We have a problem here,” and they needed to get out of the structure. It was an interesting little side note to earthquake early warning because it really didn’t take off again for decades later, until the quality of the instrumentation improved.