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Earthquake early-warning system gave 10-second alert before Napa quake felt

latimes.com

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Re: Earthquake early-warning system gave 10-second alert before Napa quake felt

#2

Post by rdl »

A few seconds warning seems like it might be kind of useless for humans, especially at 3am, but it would be cool to have this feed into automatic systems to automatically put them in a "safer" state before an earthquake hits. It might even be that 10 false positives a day are worth it to catch one real event, if the "safing" operation is relatively non-disruptive.

Re: Earthquake early-warning system gave 10-second alert before Napa quake felt

#4

Post by waiwai933 »

rdl wrote: post #2

A few seconds warning seems like it might be kind of useless for humans, especially at 3am, but it would be cool to have this feed into automatic systems to automatically put them in a "safer" state before an earthquake hits. It might even be that 10 false positives a day are worth it to catch one real event, if the "safing" operation is relatively non-disruptive.

If the system were relatively reliable, 10 seconds is actually a lot of time. During the day, it's enough time for many people to take cover. During the night, it's enough time to at least get people up and semi-oriented.

The other thing to note is that earthquakes are much shorter than most people think, usually about a minute long. 10 seconds is quite a bit of time compared to that.

Re: Earthquake early-warning system gave 10-second alert before Napa quake felt

#5

Post by melling »

To be clear, the detectors in Napa felt the tremors then transmitted the data to Berkeley. They got a 10 second warning because the tremors travel much slower than the speed of light. Being 10 seconds away means the quake is much less intense. This is helpful, but what we need is a warning for people within a few seconds of the epicenter.

Re: Earthquake early-warning system gave 10-second alert before Napa quake felt

#6

Post by argonaut »

waiwai933 wrote: post #4
rdl wrote: post #2

A few seconds warning seems like it might be kind of useless for humans, especially at 3am, but it would be cool to have this feed into automatic systems to automatically put them in a "safer" state before an earthquake hits. It might even be that 10 false positives a day are worth it to catch one real event, if the "safing" operation is relatively non-disruptive.

If the system were relatively reliable, 10 seconds is actually a lot of time. During the day, it's enough time for many people to take cover. During the night, it's enough time to at least get people up and semi-oriented. The other thing to note is that earthquakes are much shorter than most people think, usually about a minute long. 10 seconds is quite a bit of time compared to that.

I think the point is that 10 seconds of warning really translates to 0-5 seconds of warning given the time it takes to send out the warning (text, radio, emergency broadcast). Then add in time to wake and get oriented.

Re: Earthquake early-warning system gave 10-second alert before Napa quake felt

#7

Post by bigiain »

"The system works because while earthquakes travel at the speed of sound ..."

That sounds like a somewhat misleading simplification or a complete misunderstanding.

Presumably "the speed of sound in the earth" and "the speed at which earthquakes travel" is by definition the same - earthquakes just being "sound vibrations" in the earth with macro level amplitudes. I'd be very surprised if that was particularly close to what people think of as "the speed of sound" (which I'd assume means "about 350m/s").

Re: Earthquake early-warning system gave 10-second alert before Napa quake felt

#8

Post by freditup »

waiwai933 wrote: post #4
rdl wrote: post #2

A few seconds warning seems like it might be kind of useless for humans, especially at 3am, but it would be cool to have this feed into automatic systems to automatically put them in a "safer" state before an earthquake hits. It might even be that 10 false positives a day are worth it to catch one real event, if the "safing" operation is relatively non-disruptive.

If the system were relatively reliable, 10 seconds is actually a lot of time. During the day, it's enough time for many people to take cover. During the night, it's enough time to at least get people up and semi-oriented. The other thing to note is that earthquakes are much shorter than most people think, usually about a minute long. 10 seconds is quite a bit of time compared to that.

But there's no way to reliably get information to all people within ten seconds. Even if a text message alert was sent out as soon as the system was triggered, that time, plus the time for even the most phone-ready people to pull out their phone and do the necessary steps to read a message leads to basically no warning at all.
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