Editor’s note: One of the success stories to emerge from the 9.0 quake in Japan is how well its pioneering and advanced Early Earthquake Warning system performed. Researchers in California have been working on a prototype for a similar system — the first of its kind in the United States, but it faces significant hurdles. NAM’s Ngoc Nguyen spoke with UC Berkeley seismologist Dr. Peggy Hellweg, whose lab is on the forefront of efforts to design a statewide system.
How does an Early Earthquake Warning (EEW) system work?
EEW system is when an earthquake starts and we recognize it quickly and we can tell people that strong shaking is coming before it gets to them.
How did Japan’s EEW system work in the recent 9.0 quake?
In Japan, the EEW system in the magnitude 9 quake worked well. The earthquake was offshore, it started in a place with no people, which is good, but it had to get to shore before it could be measured. We measure P waves — these are faster waves that can tell us about an earthquake that don’t do much damage. It evaluated the size and it put out a warning. The region closest to the beginning of the earthquake got a warning 10 seconds before the earthquake started. In Tokyo, which is farther away, they had between 30 seconds to a minute of warning.
That’s actually a lot of time. Your main job in an earthquake is to get under your desk. If you’ve got 30 seconds of time, you’ve got plenty of time to do it. If your main job is to slow down a bullet train, that’s not a lot of time to slow down a bullet train. The bullet trains [in Japan] also have an EEW system, and they all immediately start slowing down when a big earthquake is detected. In the case of the bullet trains in the northern part of Japan, they all slowed down — none of them were derailed. Some of the people were jumbled up, but that’s better than having a derailed train.
Other things that can be done is if you have a chemical process plant, you can slow down the production and stop the flow of chemicals so they can’t leak out when pipes perhaps break in an earthquake.
Does the United States have such an early earthquake warning system?
Japan’s EEW system is the most advanced system, and it is the only one that is a nationwide system.
In the United States, there’s nothing in place. The closest thing is the prototype system in California. It’s a cooperative effort between us [UC Berkeley] and Caltech and we have some collaborators in Switzerland — people who studied with people in Caltech.
We have a prototype system that has just barely been completed and with known problems. Part of our effort is to figure out what improvements we need to do early warning. One of the improvements that we need is a lot more stations in order to be able to recognize an earthquake anywhere in the state or along our faults quickly. You really want to recognize the earthquake quickly because that is what buys you the time. And there are places in the state where we know we have faults that can produce big earthquakes where we don’t have any seismic stations.
We currently have 400 seisometers in the state — where do we need more?
There are very few stations north of San Francisco along the coast where we know there is a big fault that can have big earthquakes — mostly in the coast ranges where the San Andreas fault goes. In Southern California, in the deserts, the really big earthquakes are going to come from the San Andreas fault and out in the desert they don’t have enough stations to recognize the big earthquake quickly. There was a big earthquake in the eastern Sierras that caused a lot of shaking more or less throughout the state in the late 1800s and there are almost no stations there.
From a seismological point of view, there’s the big bear in the room, which is the Cascadia subduction zone. It starts in the northernmost part of California, and up there there’s, again, relatively few stations.
These sound like remote areas — is it important to have seisometers our there?
They are kind of remote. This earthquake in Japan, the big one, it was also remote. It was 100 miles offshore. But, a big earthquake by its nature spreads out and causes shaking over a large area, so if we can recognize a big earthquake in the southernmost San Andreas or northernmost San Andreas, we’d have the best warning time for both San Francisco or Sacramento. Or, conversely, if a big earthquake starts near the Salton Sea in southern California and it ruptures toward LA, that would be the kind of case where we have the maximum warning in LA.
Why are the seisometers located in urban areas versus remote ones?
The 400 seisometers are spread out throughout the state. As we were putting them in, we were interested more in locating earthquakes carefully where the population is, because at the time we were installing them, EEW was not one of the major goals. The major goal was measuring earthquakes — even small earthquakes where there are lots of people.
There are different objectives to measuring. The objective of an EEW is a very recent one. We’ve been working for 100 years on characterizing earthquakes: how the ground moves where we build buildings so we can make the buildings safe.
So, what are the challenges to getting such a system up and running?
The next step is three-fold. One, improve instruments and put out more seisometers. For a full blown system, it’s an important part. We can’t have a system as good as Japan’s unless we do that. Two, make the programs we have in place more robust and smart. And three, you need to have the people know what to do when they get a warning message. Before Japan went public [with its system], it spent years educating the public: if you get an early warning this is what you should do. We haven’t done that. That’s the third part of problem.
Money is important for all three parts of it. Money is very small at this point, we clearly need more money to do it. The Japanese invested more than $500 million in their system. It would take $80-$100 million over five years [to get the system working]. That’s what we estimate. Clearly, the gains outweigh that kind of investment.
Are we due for a “big one” on the West Coast?
The Pacific Northwest has a huge earthquake like Japan’s every 500 years. The average is 200 to 800 years. The last one was 300 years ago. One could say that they are due. It shouldn’t be a surprise if one came.
In California in the next 30 years, there’s a 99 percent chance of one or more 6.5 or greater earthquakes, and a 60 percent chance of there being a 6.7 somewhere in the Bay Area. The Hayward fault has one of the highest probabilities [for a quake].