Seconds before a 6.2 earthquake rattled California, phones got a warning

I live near the New Madrid. There aren't frequent earthquakes here at all, but historically when we do have one... it's a big one.

https://en.m.wikipedia.org/wiki/2011_Christchurch_earthquake

In California and Japan, decades of stringent building codes mean that most structures are likely to be safe agaist even large quakes, in the sense that occupants should survive, even if the structure itself is not repairable.

Along the central and eastern US, and in large parts of rural China, Iran, Iraq, and Turkey, amongst other areas, building codes, geology, and general preparadness and awareness (or lack) can make even comparatively small quakes deadly.

From the Rockies east, the US is underlayed by largely-intact limestone and a thick crust which can propagate seere ground movement hundreds of kilometers, up to 1,000 km or more. By comparison, along th USwest coast, being 100--200 km from an epicentre usually renders even a large quake largely harmless (though it may still be felt). Additionally, construction standards in the central/eastern US and other regions mentioned above tend to result in far more severe structural damage. Rescue, aid, and shelter capabilities may also be limited.

(In California, the principle geological hazard is fill or other soils prone to liquefaction, which can greatly amplify movement locally. Landslides may also be a concern. In mountains, rockslides.)

The guidelines 323 gives are useful for California and Japan. Elsewhere, comparable damage might occur a magnitude below those given.

Completely forget about this. Thanks for the random nostalgia hit.

Even a missile-launch alarm would typically have some opportunity to be assessed based on alert values (e.g., increasing or decreasing hostilities), and perhaps multiple sensor systems (boost-phase IR tracks plus radar signatures, known planned non-military launches, etc.).

In the case of earthquakes, their very unpredictability, the brief period of time avialable in which to make an alert (often only a few seconds, in cases a few minutes) means that manual cross-validation is all but impossible. Still, checks across multiple seismic detectors, preferably isolated from one another to the maximum extent possible, would be one potential check, though you'd still need to have multiple sensors relatively close together, as the time of propagation of seismic waves is both what provides the early alert and causes the damage. (Relative speeds of P (primary) and S (secondary) waves helps --- the p waves tend to cause less damage, but provide an earlier alert, the s waves arrive more slowly but do most of the damage.

At the surface, speed differential is about 3 km/s, meaning there's roughly 1 second of arrival differential for each 3km the observer is from the epicentre. (Subsurface waves travel faster.) Each 3km of separation of seismic stations costs 1 second of advanced warning time, plus whatever system logic and response times exist.

But given that major earthquakes can occur suddenly and without warning or pre-shocks, you really do pretty much have to be ready for anything at any time. And alerting systems need to take this into account. One option might be to have the logic on the phone itself --- it would trigger an alert, but only if some number of independent alarms were detected. One would be unlikely to trigger a false alarm, but two or three near-simultaneous alerts would indicate a major quake.

Penalising false alarms is probably the wrong approach. An engineering philosophy, of determining paths to either false positives or false negatives (each of which have high impact), and eliminating those.

I’d rather have a false alarm about a dangerous event. Then a missed alarm for the event.

Especially if the false alarms are very rare.

We met through an extreme sport hobby in which there are personal speed records to set, and setting those past a certain point are quite dangerous to ones body/life. He and I were both past said point back then.

He was living alone at the time and was woken up by the alert. Through his mind went “either this is a false alarm, or I am completely fucking dead and there’s nothing I can do about it”

Did absolutely nothing except put on his gear & went out and set a new speed record far into the “one fuckup and you’re severely injured or dead category”

Fun times.

The guy whose responsibility to push out the alert had to make a split-second decision. He knew there was a drill happening sometime that day, but his boss said (three times!) that this was not the drill. Better safe than sorry: he pushes the button. I can't really fault him.

Arguably the boss-man should face the repercussions for saying it wasn't a drill when it was, but then that's also kinda the point of the drill--to see how the team would handle a "live" situation. Maybe their interface should have been mocked or the actual alert disabled right before the drill, unbeknownst to them? So it is the drill planners that are responsible?

It's really hard to nail down an individual at fault here, rather than general bureaucratic incompetence.

"9.0 and greater. At or near total destruction – severe damage or collapse to all buildings. Heavy damage and shaking extends to distant locations. Permanent changes in ground topography. One per 10 to 50 years."

https://en.wikipedia.org/wiki/1964_Alaska_earthquake#:~:text....

And indoors:

- Drop down; take cover under a desk or table.

- Stay away from bookcases or furniture that can fall on you.

- Stay away from windows. Glass may shatter from the shakings

In Chernobyl the core literally blew up, so it's a different situation. But in Fukushima the pumps lost power and so even though the control rods were fully inserted, there was a real risk it might get hot enough to melt down anyway. That was thankfully avoided.

TL;DR: the control rods slow the reaction, but the fuel rods are still hot, and the space is enclosed (to prevent radioactive material from casually escaping) so it gets hotter and hotter without intervention. If the fuel rods get hot enough they start melting, which produces hydrogen, which can explode.

This indirect energy output is small in comparison to the reactor's output, but a small percentage times a very large power output is still sufficient to meltdown a reactor (and boil away the coolant in the process) if there's no way to remove the heat being generated.

Imagine what you'd have to do with a car engine if every car trip of 4 hours or more produced 4% power output in the form of heat for the next day after your trip was over.

And it saves lives too.

I had my last straw when I started getting alerts for wear a mask and other ridiculous crap.

I've also wondered if useable information has been received from these alerts, or if it's just a bit of psychology being used against the perps when the alert about them goes off on their phone.