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?

[sfjoe]

The collapsed Cyprus freeway was in Oakland. It's believed that earthquake waves travel horizontally through the crust and can also be reflected off of harder layers further down. If the original wave and the reflected wave harmonize they can be extremely destructive even many miles from the epicenter.

Re:One powerful earthquake?

[brian1078]

The epicenter of the 1989 Loma Prieta earthquake was in the Santa Cruz mountains, about 60 miles south of San Francisco and Oakland. Some of the worst damage was in these areas. The "Cypress Structure" of the I-880 freeway collapsed, as did a portion of the Bay Bridge. In the town, another 20 miles north of Oakland, I lived in at the time there was considerable damage to some older structures as well as to personal property.

I would have been happy to have the 15 seconds notice.

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?

Huh?

[Anonymous Coward]

What do earthquakes need to be warned early about?

Sigh

[geekoid]

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

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

It stems from an observation from a red cross worker after a earthquake in mexico.(I think 1950ish.)
That archtecture of the entrance way was an adobe arch. Arches are very strong, as opposed wooden square door frames.

Re:Sigh

[Beryllium Sphere(tm)]

There's still a door swinging in it. Depending on which way you're facing, you could get your fingers pinched in the hinges and mangled, or slammed into by a closing door and mangled.

Drop, cover, and hold is what the Red Cross is teaching, after considerable research.

First-world building are unlikely to collapse but you don't want to be hit by falling chunks of ceiling. Get under something like a table ("drop and cover") that will intercept some debris before it hits you.

The table will likely start walking across the room as everything moves up and down and sideways. Keep a grip on a leg of the table or whatever and "hold" so that it doesn't walk away from you.

Doesn't have to be a table, and improvising is good. At the grocery store you could use a shopping cart, for example.