Earthquake P-waves travel at 5km/s. To get 60 seconds of warning, you must be 300km (186 miles) downstream of the detector.
Mexico has a very unique situation [1]: the filled lake basins that Mexico City sits on have the same resonance frequency as buildings of a certain height. Earthquakes generate that frequency. So a serious earthquake 300km away can get the lake basin rocking, and that will knock down buildings of a certain height.
A detector is nowhere near as useful in California. Consider the Loma Prieta Earthquake. It occurred 90km from the damaged sections of San Francisco. Assuming there is a detector within 10km of Loma Prieta, that is only 16 seconds of warning. Give a few seconds for the alert to get out, and it's barely 10 seconds. That's not enough time to do anything other than hide under a desk -- which you can already do after the earthquake starts. Such a system would be excellent for bringing trains to a halt, but that's pretty much it.
[1] See preface of https://en.wikipedia.org/wiki/1985_Mexico_City_earthquake
* Trains may stop, preventing a literal train wreck.
* People doing delicate tasks (e.g., a surgeon, someone operating heavy machinery, even someone cooking) may lock to a safer position.
* Elevators may stop and open the doors safely, so no one will be stuck inside them.
* Air traffic control may hold take offs and maybe landings.
* All traffic lights going red may slightly reduce car incidents. Seems minor, I admit.
Also, people with little experience (me!) do NOT understand that an earthquake is happening until after the fact. Some blast alert even during the earthquake is very helpful for tourists and even immigrants.
Here's another example of what you can do with ten seconds: https://www.youtube.com/watch?v=gB6-nU2nJqM
In real life, the warning such as this would catch people by surprise. That's not to say they wouldn't be useful, but I highly doubt they would be that useful as they were on that video.
Even if I'm in my own home, I imagine it would take me at least a fifth of that time to look around and come up with a plan of what is achievable in such a short time span.
10 seconds would make a huge difference to some people.
I said that it super-helps Mexico, but that because of the specific situations in both regions, we should not anticipate getting anything like their results.
You could also cut off gas and water lines, so it would probably prevent a lot of damage due fire or flooding.
http://www.latimes.com/local/lanow/la-me-ln-earthquake-early...
Health-wise, let's say every injury has cost $30k on average (IMO a very generous estimate). Looks like there have been about ten thousand injuries or so over the last thirty years. So that's $300M.
Let's say for the sake of argument that an early warning system reduces losses by 50%. So that gives us $150M in value over thirty years. Or about $7.5M per year in value. (Less, really, because value saved in the future has to be discounted.)
That doesn't really go very far even toward maintaining an existing system, to say nothing of developing a new one. (Assuming the last thirty years is representative, that my napkin math is good, etc.)
Spoiler: it varies wildly.
Writeup: https://www.thelifeyoucansave.org/blog/id/93/how-much-are-we...
Citing: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=424523
Here are some illustrative examples:
* Consumer Product Safety Commission's (CPSC's) regulation on childproof lighters = $100k
* Federal Aviation Administration rules on airplane cabin fire protection = $300K
* National Highway Transportation and Safety Administration rules on passive restraints and seat belts = $500K
* CPSC's rules on children's sleepwear flammability = $2.2MM
* EPA's rules on fugitive benzene emissions = $3.7MM
If you're worried about getting claim-jumped by an HFT firm subscribed to the public-warning system, a few millisecond delay might allow for trade execution?
(normally on that day of the week I would have been on the lower part of the freeway that collapsed, went into work a day early that week because of the possible World Series traffic)
Would any expert reading this like to comment?
For large earthquakes, absolutely. But if you get a situation like the Canterbury earthquakes (https://en.wikipedia.org/wiki/2010_Canterbury_earthquake - 17,000+ over the span of several years) the warning system becomes useless unless it can rapidly detect magnitude and mercalli intensity.
My family lived through the Canterbury earthquakes. If you live somewhere with this hazard PLEASE prepare accordingly.
All 'early warning' systems rely on having sensors close to the epicenter that detect the waves before they propagate out to populations further away, but by that time the earthquake is already happening.
Even with the early warning, sometimes the earthquake will still be on the weaker end of the spectrum, so you brace yourself but not necessarily panic.
The 2011 earthquake started off moderately, so no one in my office ducked for cover until it really started to shake, which was already about half a minute in.
Yes actually (or go into a doorway or similar). I don't understand the derision extremely simple and basic response strategies (like the well designed and effective "duck and cover" for nuclear strikes) get when they can be absolutely enormous lifesavers. A huge amount of the human injury potential from a lot of major classes of disaster is from simple stuff like flying/falling glass and falling dense materials, all of which can do terrible things to an unprotected human body but are also absolutely trivial to deflect with another inert object. Shattered non-safety glass will cause tremendous damage to soft tissues, and someone can certainly be badly injured or killed by even a small weight like a brick or other dense objects that fall from just ceiling or high shelf height.
But none of those is going to go through heavy steel or wood. Typical work desks and tables (and of course institutional use furniture in general) are quite sturdy. Door frames tend to exhibit significant structural reinforcement as well and be away from many short range dangers. Putting an inch or two (4-6 cm) equivalent of hardwood, dense composite wood, or metal between a person and debris can be the work of seconds, and the difference between a brick landing on the table vs on someone's skull is not nothing, as is getting into a position protecting the face and vulnerable extremities and organs as much as feasible and being braced.
It's true that better architectural and infrastructure design matters tremendously and is worth continuing to work on, that if a heavy building pancakes then anyone inside is in trouble/toast, etc. But on a population survival/mass casualty reduction basis a little executed well can make a bigger difference then a lot of people give credit. The difference between death/grievous injury in many mass disasters can come down to relatively small differences in where someone is and what actions they take right before, and how practiced they are in taking the best actions promptly. Don't underestimate it.
* Elevators stop at closest floor and doors open, preventing people from being stuck between floors.
* Critical garage doors & gates at fire stations / hospitals will open, allowing emergency vehicles to quickly exit.
* Other critical doors & gates will close to prevent people from entering tunnels or other areas that could be blocked off.
* Trains will slow or stop to prevent derailments.
* Oil/Gas pipeline pressures will be reduced and valves will close to lessen impact if line is compromised.
* Hospitals alert to prevent mishaps in surgery or other dangerous areas (like MRIs).
* Airports alert to stop takeoffs/landings in case there are buckles in the runway.
In short, there are a ton of things that you can do to prevent really bad outcomes (many of which are prefaced on doing something before the power cuts out) that are much more difficult and expensive after the shaking has started.
I hope it won't rain during an earthquake or landslides may happen.
I can go all day....
Unreinforced masonry structures, tilt-up concrete buildings, and the like are far more dangerous. California has a lot of legacy tilt-up concrete structures in industrial and commercial zones.
Residences are probably more vulnerable to the resultant gas leak fires than the quake itself.
It's masonry buildings that are the most dangerous.
Either way, you should not be trying to exit a building during an earthquake because the greatest risk is debris falling on you, not the building collapsing on you.
In fact, framed houses are so safe that the current advice is that if you are in bed when an earthquake occurs, you should stay in bed. You are more likely to get hurt trying to get out of bed and find cover.
Also heard stories in the SF financial district of large glass windows popping out and falling into the street below.
Best time to sort out what to do is before the earthquake.
The reason to stay indoors is if you're in a city or next to buildings where glass and shrapnel could fall on you. If you have open space outside, then that is a much better place to be.
Generally, standing in an interior doorway is a far safer move.
You don't need to be in field in Kansas to be safe outside. If you're in the suburbs you have lawns, parking lots, or streets and there aren't windows above you. Obviously if you're in downtown LA or SF don't go outside. But there's a lot of people that don't live in, or aren't going to be in, an area with multi-story buildings completely surrounding them. You can easily get far enough away from a couple story building (parking lot) and be safe. That is much safer than inside said building.
Here's the rule of thumb "If something can fall on you outside, go to a door frame or braced structure." But I'll reiterate, it depends on your initial location.
The most useful place to be in a major earthquake is anywhere where things are not going to swing into or fall onto you. Such as underneath a desk (assuming it's not a cheap construction that will buckle under any significant weight).
If you can't escape the building, the usual advice is to find a doorway.
Secondly, if you're in the midst of huge shelves with no escape (like a home depot) get under the first shelf. the shelving won't collapse downwards, but if a neighboring shelf falls sideways you'll be protected.
Harder to do in a real emergency, but good ideas, and thinking them through can be enough to execute them when needed.
Anyway - I highly encourage taking a local CERT class if you're in the US, or finding the equivalent wherever you live.
It would've been useful in the 2016 Kaikoura quake though - watching the models* of how that fault unzipped up the east coast of the South Island should've given Marlborough and Wellington some warning.
* Here's an example: https://www.youtube.com/watch?v=z1HWet9j070
That's better than nothing.
> It's probably not enough time to run out of a building.
It could be, if the building is less than 3-4 stories tall.
"CIRES transmits earthquake early warning alerts through a network of VHF stations similar to the NOAA Weather Radio service in the United States, including use of Specific Area Message Encoding, but with faster lead times in order to issue more timely warnings within two seconds or less. CIRES offers alert systems for buildings and personal use, which also come pre-installed with the official warning sound used for earthquake alerts in Mexico. On its network of transmitters, CIRES issues required weekly tests every three hours to ensure receivers are connected to its network, as well as earthquake warnings when necessary. More than 90,000 users in Mexico City, including almost all public schools, have receivers. The Mexico City Metro additionally receives SASMEX alerts, although not for public dissemination but instead to stop trains or delay departures as necessary."
[1] - https://en.wikipedia.org/wiki/SASMEX