
Smartphone-based earthquake alert system triggered by Mexican football fans - okket
https://www.reuters.com/article/us-soccer-worldcup-ger-mex-mexico/mexicans-jubilant-over-world-cup-win-trigger-earthquake-sensors-idUSKBN1JD125
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JorgeGT
There's a lengthy explanation published in Facebook [1](in Spanish, sorry).
The important fact is that there's an app which reads accelerometers in
people's phones, which is used to trigger these "seek shelter" type alerts.
Since many smartphones shook a lot in unison, the public alert was triggered.
They apologize for this and state that they are working to avoid this from
happening again.

However, they remark that actual, scientific seismographs _did_ indeed pick
these "soccer goals" events, although since they were of relatively low
magnitude (III to IV Mercalli scale), no public "seek shelter" alert was
generated on the basis of these readings.

[1]
[https://www.facebook.com/sismologia/posts/2149439968431910](https://www.facebook.com/sismologia/posts/2149439968431910)

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acqq
Now it’s time to compare these actual measurements with all that’s written
about “what would happen if all Chinese would jump at once.”

~~~
gberger
[https://what-if.xkcd.com/8/](https://what-if.xkcd.com/8/)

~~~
chatmasta
The most insane part of that blog is that the entire world population would
fit within the state of Rhode Island.

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basicplus2
What If Everyone On Earth Jumped at Once?

Allain found that our jump would push on the Earth ever so slightly, giving it
a recoil speed of 2.6 x 10^-13 m/s. That is, in one second, Earth would move
about a hundredth of the radius of a single hydrogen atom .

[https://www.livescience.com/33383-everyone-on-earth-
jumping-...](https://www.livescience.com/33383-everyone-on-earth-jumping-at-
once.html)

~~~
pknerd
would like to read XKCD response :)

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f_allwein
Here you go: [https://what-if.xkcd.com/8/](https://what-if.xkcd.com/8/)

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natex
Here's the tweet by the Institute of Geologic and Atmospheric Investigations
in Mexico.

[https://twitter.com/SIMMSAmex/status/1008374780351967233](https://twitter.com/SIMMSAmex/status/1008374780351967233)

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amarant
Mexico City was built on a lake. I wonder if that makes it more susceptible to
such man-made earthquakes?

~~~
tomhoward
Perhaps, but that’s irrelevant in this case; there was no tremor. The alert
was falsely set off by people’s phone apps.

~~~
ColinWright
That's not entirely true - "proper" detectors did detect a "tremor".

[https://www.nytimes.com/2018/06/17/world/americas/mexico-
soc...](https://www.nytimes.com/2018/06/17/world/americas/mexico-soccer-world-
cup.html)

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tabtab
My mom warned me to diet.

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senectus1
lol nope. not unless the sensors were buried less than a foot underground
under a really big crowd.

~~~
bcraven
Well actually it happened recently in Peru:

[https://twitter.com/alerta_sismo/status/930989560896647169](https://twitter.com/alerta_sismo/status/930989560896647169)

So either someone saw that and decided to make this story up, or it does
indeed happen.

I can tell you from experience that seismometers are ridiculously sensitive-
the noise reductions that need to be done after shooting a land survey are a
nightmare.

