Problem with Earthquake calcs

[Ricsi-viragosi]

Cutting it short, earthquakes take place far away from the surface, to the point that-/+ 1 km is a small margin of error compared to depth. Well, their hypocenter does. Our basis for the magnitudes, the description for them, is the description of what it's like on the surface, not the epicenter.

For exemple, a magnitude 5 earthquake sometimes takes place 30 kilometers underground. Most earthquake feats come from physical power and shockwave, which kind of get a lot weaker after traveling tens of kilometers.

Because of this, that T-Rex making the cup vibrate is not it being High 8-C, but it being simply close.


Another problem is that most such "earthquakes" created by sheer strenght have an immensely small area of effect. Some earthquakes can take place over hundreds of kilometers, I feel like something that is only felt for a few hundred meters should not be as powerful as a normal earthquake just based on that, too.

 

[Qawsedf234]

Earthquakes should probably be looked at more thoroughly for tiering, yeah.

 

[Antoniofer]

I did notice this problem time ago, most notorious with Blood (Verse) being 8-A by pounding the ground and make rocks fall (not completely destroying the cave), and Nature's Wrath piercing through the earth crust but shaking only up to 50 m (nothing beyond that distance).

 

[Ricsi-viragosi]

Yeah, some come to mind for me to.

 

[Chariot190]

This makes sense although id also like to point out japanese earthquakes dont use the rchter scale. Jpn quakes use this. Which gets a quake's lv from groundshifts and peak ground acceleration. Earthquakes from japanese media that are given an in universe number on a scale are actually using that, not the richter scale. It seemed topical so I thought id bring it up.

 

[Ricsi-viragosi]

Our tiring is still done based on it, so it doesn't matter too much as most would still be inapplicable because of this.

 

[DontTalkDT]

We should probably be a bit more conservative in regards to really small scale vibrations. I guess some of these just don't count as real earthquakes and should hence not have the formula applied.


That being said, the earthquakes in reality not being underground has no influence on the formula. The formula we use comes from a document estimating the earthquakes caused by meteors. These are obviously surface strikes.

 

[Ricsi-viragosi]

The problem is that our standards for the scale of said earthquakes is based on data that assumes it is underground.

The tier for the magnitude is fine, but the requirements (shaking and rattling noises for 5, főr exemple) are quiet higher when you are at the very source of it.

 

[DontTalkDT]

At least as far as the document I based it of goes that isn't based on data that assumes it is underground. The mercalli value table is literally taken from that document, so in that context it probably doesn't matter.


As said, for something like shacking 10 meter surroundings one can argue that not really being a proper earthquake and the shaking hence not being usable for the formula. But for anything that is more than a bit of local shacking there should be no problem.

 

[Spinoirr]

The question is, how far away is some local shaking? Anything below 1km?

 

[Dargoo_Faust]

Finally, someone points this out on a standalone thread.

I agree with this wholeheartedly.

 

[DontTalkDT]

The question is, how far away is some local shaking? Anything below 1km?

Case by case, I guess. Partly also depends on the strength of it.

Something explicitely referred to as Earthquake should generally be fine.

 

[Dargoo_Faust]

Shaking from something tunneling deep underground (the Cluster from Steven Universe comes to mind) should also be acceptable, especially if they're reffered to as earthquakes.

 

[Andytrenom]

We are dealing with a lot of major things aren't we...

 

[Andytrenom]

Anyway, I agree that we should be more conservative with shaking feats and not immediately resort to using the earthquake chart

That said, shaking originating from the surface wouldn't be problematic by itself because of the reasons Dontalk laid out

 

[Spinoirr]

So as long its called an earthquake and not just shaking or nothing at all unless its in some extra info from a blu ray like probably for rwby

 

[Ricsi-viragosi]

If it is called earthquake then it should be fine most of the time. For exemple in Baki Yujiro shakes a building hard enough to break bulletproof windows, but nothing else shook in the city, so people describing it like an earthquake doesn't apply...

So "showing before statement" and "context matters", like always.

 

[Spinoirr]

Yeah

 

[Ricsi-viragosi]

Well, that's plenty agreements, I guess.

I don't think there is much to change on official profiles, earthquake one already assumes we are talking about a legit earthquake.

 

[Nepuko]

So, verdict?

 

[Ricsi-viragosi]

Everyone agreed, so...

Unless earthsaking in fictions shows adequate range for the potency.


For exemple, in Cyprus, was felt (it tore down castles) from Paphos to Larnaca.

A magnitude 8 earthquacke in Peru was felt all the way in Ecuador.

A magnitude 9(.1) slightly affected the whole planet, and caused damage all over Japan, moving Hushu (it's main island) by two and a half meters..

 

[Spinoirr]

So if an earthquake is made and affects a large area then its fine?

 

[Ricsi-viragosi]

I'm trying to get exemple's for differing magnitudes but I got kinda lazy and went to sleep. Will update the above comment with exemple for most magnitudes and areas they affected.

 

[Antvasima]

@DontTalkDT, Antoniofer & Andytrenom

So what, if anything, do we need to do here?

 

[Andytrenom]

@Ricsi Btw I don't know if using natural earthquakes and their range would be the correct thing, since we are talking about meteor based tremors here. What was the situation used to determine the formula itself? Like how far of an area would have to be affected by the meteor impact? That would probably be better to find out

 

[Qawsedf234]

For meteors it depends on the distance. From the earthquake calc page

• r < 60km: In this case the formula is (Magnitude at distance) + 0.0238*r = Richter Magnitude of Earthquake

• 60 Ôëñ r < 700 km: In this case the formula is (Magnitude at distance) + 1.1644 + 0.0048*r = Richter Magnitude of Earthquake

• r ÔëÑ 700 km: In this case the formula is (Magnitude at distance) + 6.399 + 1.66*log10((r/110)*((2*¤Ç)/360)) = Richter Magnitude of Earthquake

 

[Ricsi-viragosi]

That's not exactly what is being argued, Quas. It's what range it would need to have to be considered compatible with said calcs.

I guess we could use that while assuming magnitude 2 (felt, but not damaged) or something and then keep putting a radius until we get the distance for the differing magnitudes.

For exemple:

To get magnitude 3, while assuming magnitude 2 is at the border (point until it's felt), I got 42 kilometers. (2)+0.0238*42

So according to this, a magnitude 3 earthquake caused by a meteor would be felt (have magnitude 2) from 42 kilometers away. Does this seem plausuable or is there an obvious problem that I missed?

 

[Qawsedf234]

Yeah that seems good to me. Although maybe something more along the lines of "can be felt by distant observers" would be a better metric for usability.

 

[Ricsi-viragosi]

Well, yeah, just wondering how far they would need to be.

To be honest tough, I don't think we need to be too strict. If there are people 400 meters away feeling it and the author draws atention to this, I feel the intention is clear.

 

[DarkDragonMedeus]

Yeah, I do agree that simply shaking the ground and not causing collateral damage being justified for an 8-B rating is shaky (Pun intended). Magnitude from a distance Earthquakes are still good. And if there's a statement about an Earthquake attack having a high magnitude, then it's good. But simply shaking the walls by yelling is weird; especially for characters like the Anime version of Manfred Von Karma.

 

[Kisaragi_Megumi]

ffs 7-A Fate gonna be gone again because this? C'mon man....

 

[Schnee_One]

Probably, depends on the conclusion

 

[Ricsi-viragosi]

I mean, a conclusion is already reached. Depending on the magnitude of the fate earthquake, it would need to have quiet a widespread effect.

 

[Schnee_One]

Literally happened in a cave

And it got 7A

 

[DarkDragonMedeus]

If the earth quake legit happens underground, and/or is shown to be widespread, it's still legit. But shaking a small area by punching the ground or jumping not so much.

 

[Schnee_One]

Not sure if Cave applies to that. But it's not widespread to my knowledge

 

[LSirLancelotDuLacl]

Considering Angra Mainyu was affecting a Cave at least 3 KMs across and shaking it so heavily the geography of the area was getting violently shifted and destroyed and the whole cave going down, I really doubt Fate will be much affected.

Regardless I do agree with this. It felt a little odd at times that there was just shaking around and the farthest in scope you could see was like, a few dozen meters of stuff shaking and it would still be accepted? Am all for this,

 

[DarkDragonMedeus]

Also a certain purple character whom I shall not name due to not wanting to get involved at all here also may need a downgrade

 

[Kisaragi_Megumi]

Who?

 

[Hellbeast1]

Also a certain purple character whom I shall not name due to not wanting to get involved at all here also may need a downgrade

Thanos