"... that are responsible for severe earthquake damage, like lightning before thunder. Using the P waves, a local data-processing center can calculate the likely reach and magnitude of a quake moments after it begins. The resulting alert, dispatched at the speed of light, usually beats the S waves, which ripple through rock at about two miles per second. To call the warning 'early' is generous. It usually arrives between a few seconds and less than a minute ahead of the quake—advance notice that, in duration, is somewhere between a sneeze and a red light.... In the past few decades, more than half of earthquake injuries in the U.S. have been caused by people or things falling—two occurrences easily avoided if you have time to take cover beneath a sturdy piece of furniture. For those who are landing planes, assembling electronics, operating cranes, or drilling into molars, even the smallest warning would be welcome. You might have just enough time to lock the wheels on your wheelchair, or to remove your scalpel from your patient’s chest.... The brief window for action created by the systems doesn’t allow for hesitancy or confusion.... To some, an advance warning might seem like an invitation to evacuate, or a prompt to check on other family members. Many earthquake myths persist—doorframes are no good, it turns out—and there are still gaps in public awareness: What do you do if you get the alert in bed? (According to fema, you should turn face down and cover your neck and head with a pillow.)"
From "There’s an Earthquake Coming!/The newest warning systems give users ten seconds’ notice. What can be done in that time?" (The New Yorker).
पोस्ट्स
२४ टिप्पण्या:
10 seconds? Reminds me of that old SNL sketch where Dan Akryoid has a device that warns of mid-air collisions 15 seconds in advance.
Most humans will just be stunned into motionlessness in those 10 seconds. If you really want it to have an effect, drills might be conducted on a regular basis like our local tornado warning sirens here on every 1st Wednesday of a month at noon. Of course, the problem is that people will then spend the 10 seconds wondering if this is just a drill.
Inside the home it would give me time to go to a dependent. Elsewhere, not so useful.
Automated systems can start shutdowns as soon as warning is received. 10 seconds is not much, but it is something. Also, '10 seconds' assumes a given distance from the epicenter. Greater advance warning would be available for greater distance, but I do not think you could get more than 15-30 seconds.
"The resulting alert, dispatched at the speed of light,.." P wave--compression waves--travel at the speed of sound, not light. Don't we wish reporters knew a bit more science.
@Unknown
You're making a mistake. The alert isn't sent out as a P wave or a sound wave. Once the P wave is detected a warning goes out that can be picked up on your mobile phone.
As somebody who does research on individual hazard adjustment (even in earthquakes), I can say with certainty this article is ridiculous. Research shows that even people in earthquake prone areas (New Zealand, Taiwan) do not make immediate hazard adjustments. They initially freeze. Even when they have experience and know what to do, they freeze. That makes the extremely small amount of "advanced notice" pretty useless.
As someone who studies disaster and, in particular, human adjustment to hazards, I can tell you these prewarnings are pretty meaningless. Research consistently shows that people, even in earthquake prone areas and across nationalities, freeze before taking action. Muscle memory through drills might help, but it would have to be pretty realistic (i.e. no advanced warning in any of the drill scenarios).
Hmmm. Some years ago I was at a technical conference where I recall listening to a research presentation about using an AI engine, based IIRC on neural nets, to monitor the accelerometers on cell phones in order to detect the onset of earthquake events. It promised to give up to a 30 second warning in some cases. Thirty seconds isn’t much. but it’s enough time to start opening doors at fire stations (the presenter claimed that the most common reason for a delay in first responders was garage doors being jammed at the police and fire stations). Thirty seconds might also warn people to get off bridges and out from under bridges, if they can.
If you are at home and not in bed asleep or in the shower or on the toilet or committed to anything else impossible to wrap up in under 10 seconds, that may give you enough time to either get outside or get under a desk or a table, so I say let’s do it.
Sent as a ping on our mobile phones. We have 10 seconds.
Phone: Ping!
Me (asleep in bed): Huh, honey? Was that your phone or mine?
Wife (deep in REM): Wha...What?
Me: I said...
In 2014 and 2015 we rode out some pretty powerful shock waves in our 10th floor Tokyo apartment.
For all of the ones that originated outside of the city, our wall intercom would beep loudly and a women's voice would come on saying the equivalent of 'danger, take cover' in Japanese.
It seemed that we were getting a ten to twenty second notice of when we'd feel the shaking. Not a lot, but enough to brace yourself or get under a doorway or table.
I lived for several years in an earthquake-rich zone - the Philippines. One time I was teaching a class on the second story of a building when all my students suddenly jumped up and ran down the stairs and outside. Only after that did I feel the earthquake that prompted their flight and I was still standing in the classroom.
Ernest
Since I live in earthquake territory, not sure how much of this is really helpful. The most common thing I see in my earthquake app are pet owners who get a bit of a heads up because their dogs react just ahead of the shaking. Sounds as if it confirms what the animals already get naturally.
As Yancey noted above, you tend to be stunned into motionlessness in those ten seconds. And if it's the dead of night it takes that long just to shake off sleep and react.
Ten seconds is a lot of time with a big earthquake that itself take some to really get going. I remember watching local nbc news in the 80s, seeing Kent Shocknek on live tv start moving and dive under a desk and clearly giving us enough time to realize another aftershock was coming our way 25 miles east of the studio
Put you head between your legs, and kiss your ass goodbye. That's about 10 seconds.
That amount of warning would be hugely beneficial - it would give you time to get off a ladder, turn off the stove/oven, get away from windows, to not drive under an overpass if you're on the freeway, click "Publish Your Comment", etc.
Ten seconds is better than no warning. It’s enough time to move away from windows or other objects that fall. I can get a lot done in 10 seconds. Just ask Mrs. MJB.
In case you’re not earthquake experienced, we usually spend the first few seconds looking to what sways and how far to determine if we are having a quake. So this will allow a quicker movement to the ensuring safety stage. Yancey, one only freezes in the first earthquake. After living in California awhile most of us have speedy reaction times. Personally I do better in emergencies than average. I’m calm and time seems to slow down a little when the shit hits the fan, or the fault shifts, as it may be. The missus and I just bought a house on the San Jacinto fault line and that’s why no one will ever build behind us.
Reminds me of the Hawaiian incident a few years ago falsely warning of a missile attack. How will this alert system be tested? Does a P wave automatically trigger an alert without any human intervention? (There goes the 10 seconds.) Can the alert system be hacked, or false P waves generated by bad actors? Doesn't seem like a workable idea at present.
Right, so NONE of these alerts are going out at the speed of light in a vacuum ... because matter matters. And they're not going out at speed of light in air either.
Unless you're shooting a storm trooper laser. We can beat that with a Wal*Mart slingshot.
If the epicenter of the quake is, for example, 100 miles off Market St. in SFO, then there may be a few seconds warning between the fast waves hitting a computer somewhere and the actual quake waves hitting the Golden Gate.
But, even in fiber optic based transmission systems the transmission speed is MUCH less than the speed of light. Oddly, it's not much faster than copper - about 75% of the speed of light in a vacuum.
Then the signals have to process in the computer (which is not fast) then they have to be sent to warning systems (cell phone systems) then those have to be delivered. Etc.
I suspect automatic shutdowns might save some lives (taking a train from 25mph->15mph is a good thing!) but I'd be surprised if people save people.
However up in Oakland maybe they can get a full minute warning and shut down the bridge and flush a few hundred cars off. Get the commuter trains to a full stop. Bring the elevators down to the ground floors and get the doors open. Dispatch rescue teams to staging areas before the cell towers all fall down. All good stuff.
-XC
It sounds as though this would be the most beneficial for people working in sensitive environments. Living in Southern California my entire life my thought process during an earthquake is as follows:
I hear something that makes me pause.
Is that an earthquake?
Look at hanging lights or dogs.
Oh, it's an earthquake.
Do I need to get up or move?
Wow, we had an earthquake. Wonder if my sister felt it?
or
Wow, this is a long one. Maybe I should move?
Holy crap, that was kind of big I probably should have moved...Ok, next time. Wonder if my sister felt it.
The coolest earthquake experience I've had was in 1986. We were floating in a pool and when we heard the earthquake coming we looked up and got to watch as it traveled along a long row of palm trees. Nobody was hurt in that earthquake.
The scariest was in 1987. I was on the 14th floor of a building in Los Angeles. The amount of swaying was awful.
One thing I do worry about since the 1989 earthquake is being under an overpass during an earthquake. I try to avoid being forced to stop under them, but sometimes it is unavoidable.
Since the amount of warning time depends on the velocity differential of the P-waves and the S-waves, the closer you are to the epicenter the less warning time you will get. But the closer you are, the stronger the shock and the more warning time you need.
"doorframes are no good, it turns out"
A comedian in SF made the same observation a couple decades ago. "It's not like you see rubble, rubble, door frame, rubble, door frame. No, you just see rubble."
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