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masamunecyrus t1_ity8j8u wrote

Reply to comment by Willinton06 in How Google Alerted Californians to an Earthquake Before It Hit by max-venum

By whom? Japan has had earthquake early warning since 2006. Mexico City has had it since 1991.

These systems do not predict earthquakes. They process seismic data in realtime, and when they detect an earthquake send out an alert faster than seismic waves travel through the earth (~3.5 km/s vs. the speed of light, minus processing times).

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sumelar t1_iu1jtyd wrote

You think everyone had a smartphone in 1991?

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ShoulderGoesPop t1_ityatuv wrote

So they predict an earthquake will happen at a specific location before it happens because it already happened at another specific location.

So they predict earthquakes.

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masamunecyrus t1_ityckrj wrote

Uh, no?

An earthquake happens at a specific place. Seismic waves then radiate out predictably from the epicenter.

Think of it like throwing a rock into a lake. The "earthquake" occurs when the rock impacts the water. The waves then radiate out on every direction. If you have sensors out on the lake, you can predict when the waves will teach the shoreline.

You're not predicting when the rock impacts the water (the earthquake). You're predicting when the waves, which have already been generated and you've already observed, will travel from point A to point B.

Does this make better sense?

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My-Left-Plate t1_itydrgt wrote

I mean I was with you until the condescending on. OP is also right. The earthquake can be the seismic slip but it could also be where the shaking is happening g on the surface. And for most people, it’s the latter.

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masamunecyrus t1_itye3d7 wrote

>I mean I was with you until the condescending on.

I have no idea what you're referring to. What part of my response was condescending?

I have a PhD in seismology, and OP asserted false information. I am trying to teach why it is wrong in a way that makes sense to people unfamiliar with the field of seismology. What would you rather I say?

Conversely, I thought the OP's tone was very condescending. Specifically, this part.

> So they predict earthquakes.

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My-Left-Plate t1_ityf357 wrote

The part where you said ‘uh, no?’

Now you double down with your PhD and ‘false information’ and ‘trying to teach’. You may be trying but you are a bad teacher. Step one in teaching is compassion and connection and you are doing neither. You are condescending from authority and it shows.

Read what I said. For most people the word earthquake means the earth quaking where they are. Which means OP is dead right.

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masamunecyrus t1_itygcbo wrote

I give up. I don't know why I bother commenting on reddit posts, anymore, and your response is why. This is not the same website as it was long ago, and it just keeps getting worse every year. Perhaps I'm finally done after many years of saying I would be. 🤷

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My-Left-Plate t1_itzv0gj wrote

Don’t let the door hit you on the way out!

Maybe you should take a walk and figure out why you don’t have any friends. Hi t: it’s because you a smug know-it-all who isn’t very nice.

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AnimationOverlord t1_ityntdg wrote

You are suggesting a scenario where the earthquake begins right beneath you instead as the epicentre instead of further away, in which case radio waves can give early warnings?

He did mention that, and was right at that, but it’s not the focus here.

Edit: but whether it’s a possible scenario I don’t know

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My-Left-Plate t1_itzusix wrote

That is neither what I am suggesting or what others are suggesting g.

It’s real simple, maybe your PhD is getting in your way.

For most people, the word earthquake means the earth is shaking where we are. We aren’t dumb, we all understand that the actual seismic plate slip or whatever happened a thousand miles away or something g, maybe way deep in the earth. And we aren’t dumb, we all know that the wave travels through the mantle and the crust at different speeds to get to different places at different times.

What the OP said is entirely true. The earth quakes at one place, phones detect it, and they tell other phones that an earthquake is coming to their location in like 10 seconds.

OP is entirely correct. They are predicting earthquakes based on other earthquakes.

Your usuals of the word might be correct in the technical parlance, but it is wildly incorrect in the popular, common, context. We all get where earthquakes come from, but none of us is calling the event way down in the earth the earthquake.

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