Last week's earthquakes in California were a useful reminder to West Coast residents to review their preparations for the next big earthquake — or, really, any natural disaster.

But they also offered an opportunity to check into the status of the ShakeAlert early warning system, which could provide a warning of a few seconds or possibly a minute or two before strong tremors arrived.

The science behind the ShakeAlert system is fascinating. Quakes produce two types of energy that radiate out from the epicenter: primary waves, which scientists persist in calling p-waves, and secondary waves, which are called (you guessed it) s-waves. As it turns out, the primary waves travel faster than the secondary waves and typically don't cause much destruction. It's the s-waves, lagging a few seconds behind, that cause the damage.

It's the gap between the p-waves and the s-waves — sometimes lasting 10 seconds or so, sometimes longer  — that offer the opportunity for the ShakeAlert early warnings.

You may be thinking, what good will 10 or 15 seconds advance warning do for me? Well, potentially, it could give you time to take cover under a desk and hold on — actions that could save your life.

The ShakeAlert system also could be extremely useful in terms of preventing what the U.S. Geological Survey calls "cascading failures." (The USGS has been working to develop and implement the system across the West Coast.) For example, it says, isolating and shutting down utilities before shaking starts could reduce the number of fires that start after a quake. A few seconds of warning could be sufficient to slow trains and taxiing planes, to prevent cars from entering bridges and tunnels or to automatically shut down and isolate industrial systems.

Sounds promising, right? And, in fact, the ShakeAlert system is up and running today from Canada to the Mexican border, according to Leland O'Driscoll, the ShakeAlert project manager who works at the University of Oregon. 

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But here's the catch: The system needs more sensors installed before it's fully functional in Oregon. O'Driscoll told The Oregonian newspaper that the state needs 75 percent of 238 statewide sensors in place. By August, the number of sensors in place should be up to 125, with more coming last year.

A bill introduced in the Oregon Legislature would have contributed enough state money to the system to have it be fully functional by 2023, but funding specifically designated for ShakeAlert was eliminated during negotiations on the measure — a disappointing and short-sighted result. The money would not have paid for just the sensors, but also would have funded systems to deliver warnings to the public — which, after all, is kind of the point. O'Driscoll told The Oregonian that ShakeAlert advocates planned to renew their pitch to the Legislature's 2020 session, and this certainly sounds like an investment legislators should make. 

The system will experience some growing pains, but those are to be expected. For example, as The Oregonian reported, neither of the recent California quakes (which thankfully didn't cause any major injuries) triggered the system, and officials said they would look at modifying the criteria and lowering the threshold at which alerts are issued.

But that could lead to another issue: If the system issues a batch of alerts for small earthquakes that people may not even be able to feel, that runs the risk that people eventually will just ignore the notifications. "If people get saturated with these messages it's going to make people not care as much," Robert de Groot of the Geological Survey told The Associated Press. 

And that's possible. But it also seems likely that scientists, given enough time, will be able to fine-tune the system.

Besides, we suspect most Oregon residents will agree with something that O'Driscoll told The Oregonian: "People would rather have a warning without shaking than shaking without warning." (mm)

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