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Comment by _tom_ | Hacker News Reader

Why should we "create" categories. There should be an algorithm for determining level. Input 1000 miles an hour, you get a category.

Earthquakes don't have an upper limit. It's just a function of energy.

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I seem to recall a video (perhaps KurzGesagt) that a magnitude 25 earthquake would overcome the binding energy of Earth - the planet would be in separate pieces. That definitely is an upper limit: when the "earth" in earthquake literally cannot take more.

Earthquakes are sort of naturally limited though. A 9.0 is going to be catastrophic no matter what, and while I’m not saying a 10 couldn’t happen it would probably be something like once in a billion year event.

10.0 is firmly in "if it happens nobody's gonna be around to care what it's designated" territory I think. There's a practical point at which the death tolls are going to be sufficiently high that the number probably shouldn't matter.

Though in tornadoes there definitely are EF-4 designated twisters that are hotly contested online as being truly EF-5; often that's down to where damage occurs in the lifetime of a tornado though and it being difficult to prove windspeeds when a system is moving through, e.g.: trailer park vs an industrial park.

I don't think it's quite as cut and dried as that. A 9.5 hit Chile about 60 years ago, and about 95% of the most directly hit town survived. Which is not to minimize it - there were thousands of fatalities - but it was human scale tragedy, not apocalypse.

An estimate of the upper limit of an earthquake is approximately 10. It's a function of max rock strength.

It’s actually a function of energy released. The earthquake can get bigger if the fault slip is larger. A magnitude 12 quake is technically possible but requires an entire hemisphere to slip 500 meters. There’s a really interesting paper that takes the moment magnitude scale to its logical extremes.

PDF warning: https://www.fujipress.jp/main/wp-content/themes/Fujipress/pd...

Fair enough - something like rock strength and rupture length. Good paper. Thank you

I seem to recall something about the asteroid that killed the dinosaurs producing a magnitude 11.

I wonder what the collision that produced the moon rated?

Well, as long as they are only doing those in papers!

With regard to hurricanes, we are an active participant in creating the level of need for new terminology.

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