An Early Warning System For Earthquakes

Iphtashu Fitz writes "Would 15 seconds be enough warning time to prepare for an earthquake? It certainly wouldn't be long enough to evacuate from where you live, but it may be just long enough to get out of a building or brace yourself in a doorframe or under a solid desk. Italian scientists may have discovered a way to measure the initial shockwave of an earthquake two seconds after it starts, and from it predict the extent of the destructive secondary wave that will follow. It typically takes twenty seconds for the secondary wave to spread 40 miles, so sensors that can transmit warnings at the speed of light may provide just enough warning before a major quake for people to brace themselves. Even more importantly, such a warning could allow for utilities like gas companies to close safety valves, preventing potential fires or explosions in the aftermath of the quake."

Comments

One powerful earthquake?

[solafide]

It takes 20 seconds for it to travel 40 miles? How much power has that secondary wave lost in those 40 miles? Wouldn't it take one really powerful earthquake for you to need to take cover 40 miles from the epicenter?

(I'm not an expert on earthquakes, but 40 miles seems like a long way for the earthquake to travel.)

Re:One powerful earthquake?

[Beryllium Sphere(tm)]

1985, Mexico City, buildings collapsed when the center of the earthquake was 400 km away. That one was unusual but it shows what's possible.

The other thing you can do with 10-20 seconds of warning is apply emergency brakes on the bullet trains, which I believe Japan has arranged to do.

Re:One powerful earthquake?

[Bif Powell]

>>Mexico City, buildings collapsed when the center of the earthquake was 400 km away.

Cinco de Mayo probably has that kind of blast radius as far as knocking over buildings in Mexico.

Re:One powerful earthquake?

[davidsyes]

I was lucky that day. I had only minutes before left Grand View (Chinese) Restaurant (they changed names to Fortune after the quake) with a few cartons of food and couldn't decide whether to go straight back to Milpitas or to dart over to Embarcadero and shoot a few pictures.

By the time I'd decided it wouldn't be good to get the food late to some people I told about the restaurant, when I decided to head on south, I was barely out of Oakland, somewhere south of Cypress on 880 because. Had I gone to SF, I'd have been SOMEwhere on the Cypress. It's possible I could have also been somewhere before the fallen deck section, but that all could have depended on how many people on the Cypress would have been in my way (back then I might have wanted to speed, might have just relaxed and slipped in and cranked up my Depeche Mode cassettes, (but instead I kept the KGO talk on), blah blah blah...) and I am SURE I'd have probably died that day had I not just taken the food straight to my friend.

I think I was barely north of the Marina shopping outlet when my steering started acting up. I couldn't believe my barely 1 year old car was acting up. Then the radio went out. There wasn't too much traffic in that section, so my eyes fixated partly on the road and partly on the trees. When I saw them swaying, I knew my car was OK, but the radio was hissing. Only a few weeks earlier IIRC, KGO's antenna near the Dumbarton Bridge went out and needed repairs, so I thought they were having problems. I tuned to other stations only to hear noise and mostly silence, but sporadic bits mentioned major earthquake.

Fortunately, the roads don't open up like they do in hollywierd flicks. Fortunately it wasn't in the thick of commuter traffic, or there might have been collisions all up and down the freeway for dozens of miles if anyone freaked and lost control of the car. I was fortunate that day...

Safety valves?

[EaglemanBSA]

There would still be gas in the main lines, how would shutting a safety valve keep a broken pipe from leaking gas already in it?

Re:Safety valves?

[TransEurope]

Great idea. Another thing is to automatically
interrupt the electricity in the buildings to prevent
fires caused by short-circuits. But what would it cost
to equip all houses in San Francisco (or any big or medium
sized city) with such systems? Maybe billions of dollars.

Radon

[APE992]

My geology professor has gone over it again and again, Radon could potentially be an early warning system in some cases. Naturally the stuff leaks out of the ground, before an earthquake more of it is supposed to come out due to the shifting of the ground up to the earthquake. This could be months, days, minutes that this is detectable. Someone with a better understanding please correct anything and add to this.

Not enough time

[El Cubano]

Would 15 seconds be enough warning time to prepare for an earthquake?

Nope. But a few hours to a few days would be lots better.

Re:Not enough time

[Sibko]

Would 15 seconds be enough warning time to prepare for an earthquake?
Yes, it would.

I worked at a shipping warehouse, and I can tell you that even 5 seconds of warning prior to an earthquake could save the lives of workers. The goods are stacked up 4-5 stories high, and each crate easily weighs half a ton or more. It wouldn't take much shaking to knock the top ones down and crush people.

Considering the size of the building I worked at, the only real options available would be to either get out of the isle as fucking fast as you could, or to get under the girders supporting the crates. 15 seconds of warning would be plenty of time for me to hop on my pallet-jack and drive to the dock before anything happened. So yeah, even 15 seconds of warning could mean the difference between being alive, and being crushed under a crate of peanutbutter.

Doesn't japan have something like this?

[Hays]

I thought the high speed trains in Japan would stop in the event of an earthquake (before the earthquake actually hit them), http://en.wikipedia.org/wiki/Shinkansen

"In the event of an earthquake, an earthquake detection system can bring the train to a stop very quickly"

Anyway, the idea of a broadcast system to warn of an earthquake is pretty obvious, the engineering task of doing it right without false positives is pretty difficult I bet.

Loma Prieta deaths from this.

[Ungrounded Lightning]

"... brace yourself in a doorframe ..."

this is a myth. The only thing this acomplishes is broken fingers.

A very dangerous myth, too. Most of the deaths in Loma Prieta may have resulted from this myth.

There were 57 deaths attributed directly to the earthquake, and 42 of them were in the Cypress Street Viaduct collapse.

At the start of the earthquake, the drivers stopped. Because of the myth, most of them tried to stop under the arches. When the strucutre collapsed, the arches came all the way down to the pavement, pancaking the cars beneath them, while the regions between the arches had enough space that it was possible, in many cases, to survive the collapse itself.

- - - -

Of course a lot of the deaths there are attributable, not just to the quake, but also to governmental interference with volunteer rescue attempts.

Most of those who survived the initial collapse were still trapped in their cars or the structure itself. When the quake hit virtually all of the the nearby citizens dropped what they were doing (along with any inter-group animosity) and immediately began rescue efforts. (A notable part of this was workers at a nearby warehouse improvising an elevator using a dumpster and a forklift.) The pulled quite a few out of the collapsed structure's "sandwitch" in the first half-hour or so (at considerable risk to themselves, especially given the risk of further collapse or rolling debris due to aftershocks). Then the authorities arrived.

The police kicked them out and cordoned off the area to await the official first responders. They eventually arrived - around sundown. Then they had insufficient light (given the power failure) and mainly waited around further for portable lighting to arrive. It was several hours before rescue attempts, with a smaller force of official rescuers, resumed. (Of course by then the "golden hour" had long since expired and those who had been in shock were now dead or beyond hope.)