Earthquakes in small areas

[Kulf_Boba]

What is the minimum length that an earthquake zone must have so that the earthquake formula can be used?

Example: In this feat a character shakes a cave causing rocks to fall, can the formula be used?

 

[KLOL506]

@DontTalkDT

 

[DontTalkDT]

I would say a cave that big is good enough to use it.
The formula itself specifies no fixed lower limit, the lower limit comes just from us drawing a line. So no specific number is attached to it other than that the area should be reasonably large.

 

[KLOL506]

I would say a cave that big is good enough to use it.
The formula itself specifies no fixed lower limit, the lower limit comes just from us drawing a line. So no specific number is attached to it other than that the area should be reasonably large.

Would something like localized shaking on the Pyramid of Giza work? It is pretty massive after all. Where would we draw the line? Starting at 100 meters at the bare minimum?

 

[ElajRuengies]

Would something like localized shaking on the Pyramid of Giza work? It is pretty massive after all. Where would we draw the line? Starting at 100 meters at the bare minimum?

Why would there be a lower limit? I have a calc of two warehouses being shaken which comes out to Wall level+, so this is kinda important to me

 

[Migue79]

It’s because I believe in some revision that happened a long while ago, localised shaking that only took place in a very small area were discounted as proper Earthquakes, and as such not to be treated and calced as such.

 

[KLOL506]

It’s because I believe in some revision that happened a long while ago, localised shaking that only took place in a very small area were discounted as proper Earthquakes, and as such not to be treated and calced as such.

Unfortunately that is indeed the current case. But the cave seems pretty large and a pyramid like the ones in Egypt would be much bigger.

 

[ElajRuengies]

It’s because I believe in some revision that happened a long while ago, localised shaking that only took place in a very small area were discounted as proper Earthquakes, and as such not to be treated and calced as such.

Unfortunately that is indeed the current case. But the cave seems pretty large and a pyramid like the ones in Egypt would be much bigger.

Sauce or it didn't happen Yeah but isn't that why there's a radiated waves equation? Since it's not like actual tectonic activity is used for shaking. (Plus shaking is only level 4 anyway, since it's minor rattling that doesn't damage anything and is only felt)

 

[KLOL506]

Sauce or it didn't happen Yeah but isn't that why there's a radiated waves equation? Since it's not like actual tectonic activity is used for shaking. (Plus shaking is only level 4)

That's... exactly what happened. We tried radiated waves in those localized sections. We got ****** instead.

 

[Migue79]

That's... exactly what happened. We tried radiated waves in those localized sections. We got ****** instead.

Yeah… MCB level room shaking OwO

 

[ElajRuengies]

That's... exactly what happened. We tried radiated waves in those localized sections. We got ****** instead.

Hold on, what do you mean by "Localized Sections"? Or "Got ******"?

 

[KLOL506]

Yeah… MCB level room shaking OwO

Actually, now it's no longer MCB using the "Other" method, got knocked down to 15 tons of TNT.

 

[KLOL506]

Hold on, what do you mean by "Localized Sections"? Or "Got ******"?

Meaning, earthquakes involving localized sections not spreading out to large areas like towns or cities or being felt by neighborhoods got axed.

 

[Migue79]

Actually, now it's no longer MCB using the "Other" method, got knocked down to 15 tons of TNT.

Still unreasonably, but hilariously high.

 

[ElajRuengies]

Yeah… MCB level room shaking OwO

Actually, now it's no longer MCB using the "Other" method, got knocked down to 15 tons of TNT.

Wait wait wait- how was over 15 tons of TNT gotten by shaking a room? Was the equation used properly? Assuming the room was a generous 50 meters in radius and standard Richter 4 shaking, that'd be

• 4 (Magnitude felt) + 6.399 + 1.66*log((0.05/110km)*((2*pi)/360)) = 1.93209478 (Actual Mag of radiated weaves)
• R.W. Mag to Joules: 10^(1.5 * 1.93209478 + 4.8) = 49,904,782.83 joules, or less than 12 kilograms of TNT

So how was over 15 TONS gotten? Can I see this calc?

Meaning, earthquakes involving localized sections not spreading out to large areas like towns or cities or being felt by neighborhoods got axed.

Still unreasonably, but hilariously high.

What/when was this?

 

[Migue79]

Why are you using the formula that requires the radius to be > 700 km?

You deadass got the earthquake from 50 meters to be higher than when it’s at the epicenter, which doesn’t make any sense for obvious reasons.

 

[KLOL506]

Wait wait wait- how was over 15 tons of TNT gotten by shaking a room? Was the equation used properly? Assuming the room was a generous 50 meters in radius and standard Richter 4 shaking, that'd be

Earthquake page says as much. I'm using a Pyramid of Giza for my example.

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

Giza is 230.33 m at its base per side. Assuming it's shaking so that peeps feel it, Magnitude 4.

r is distance in km. So 230.33 m is 0.23033 km.

(4) + 0.0238*0.23033 = 4.005481854 on the Richter scale.

Formula: 10^(1.5*(Richter Magnitude)+4.8)

Calc: 10^(1.5*(4.005481854)+4.8)= 64301748282.8 J or 15.3685 tons of TNT (8-B)

 

[KLOL506]

Why are you using the formula that requires the radius to be > 700 km?

But... I didn't do that.

You deadass got the earthquake from 50 meters to be higher than when it’s at the epicenter, which doesn’t make any sense for obvious reasons.

I didn't do that either. I just used the formula for finding the Richter magnitude first (I used the R < 60 km variant), then I used the "Other" formula.

 

[KLOL506]

What/when was this?

Looking for the CRT that DontTalk made, gimme a bit.

 

[Migue79]

KLOL, I wasn’t talking to you.

 

[KLOL506]

KLOL, I wasn’t talking to you.

Ah, okay.

 

[ElajRuengies]

Why are you using the formula that requires the radius to be > 700 km?

...
[rereads the Earthquake calculations page]
Huh.
In my defense I was going off of a Shaking Feats blog, which used the r ≥ 700 km equation for every distance.

You deadass got the earthquake from 50 meters to be higher than when it’s at the epicenter, which doesn’t make any sense for obvious reasons.

A shake from radiated waves that feels like a Level 4 Earthquake from really close, but has nowhere near the same affected area as a Level 4 Earthquake, would reasonably be equivalent in energy to a waaay smaller earthquake- at least that was my thought process.

Earthquake page says as much. I'm using a Pyramid of Giza for my example.

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

Giza is 230.33 m at its base per side. Assuming it's shaking so that peeps feel it, Magnitude 4.

r is distance in km. So 230.33 m is 0.23033 km.

(4) + 0.0238*0.23033 = 4.005481854 on the Richter scale.

Formula: 10^(1.5*(Richter Magnitude)+4.8)

Calc: 10^(1.5*(4.005481854)+4.8)= 64301748282.8 J or 15.3685 tons of TNT (8-B)

Ah, so that's where that comes from.

My question now becomes where did the <60 km and 60 ≤ r < 700 km equations come from, because they don't have a log like the r ≥ 700 km equation did. Earthquake power is logarithmic right?
(I swear I'm not continuously asking for sources to eat up your time- I'm genuinely curious)

 

[KLOL506]

Looking for the CRT that DontTalk made, gimme a bit.

Found it: https://vsbattles.com/threads/problem-with-earthquake-calcs.61510

 

[KLOL506]

...
[rereads the Earthquake calculations page]
Huh.
In my defense I was going off of a Shaking Feats blog, which used the r ≥ 700 km equation for every distance.

A shake from radiated waves that feels like a Level 4 Earthquake from really close, but has nowhere near the same affected area as a Level 4 Earthquake, would reasonably be equivalent in energy to a waaay smaller earthquake- at least that was my thought process.

Ah, so that's where that comes from.

My question now becomes where did the <60 km and 60 ≤ r < 700 km equations come from, because they don't have a log like the r ≥ 700 km equation did. Earthquake power is logarithmic right?
(I swear I'm not continuously asking for sources to eat up your time- I'm genuinely curious)

Couldn't say, after I heard that localized quakes were no longer valid, it kinda fell out of my usage so I didn't keep much track of what happened after.

 

[ElajRuengies]

Found it: https://vsbattles.com/threads/problem-with-earthquake-calcs.61510

Thanks!

Couldn't say, after I heard that localized quakes were no longer valid, it kinda fell out of my usage so I didn't keep much track of what happened after.

I'm asking this, because for the <60 km equation, even if the radius is 0- as in- the literal epicenter is inside the opponent and they feel "shaken", then the power of the radiated waves will be-

• (4) + 0.0238*0 = 4
• 10^(1.5*4+4.8) = 6.31 gigajoules / 15.08 tons of TNT.

Obviously is going to make massive results for small things being shaken, since the minimum power from this equation is 15 tons of TNT. This is because in the r < 60km equation, distance can only add to the Magnitude, not subtract. (And Mag 4 effects are going to be the lowest value anyone will bother doing earthquake calcs for)

But as I've said earlier, A shake from the radiated waves of some attack that feels like a Level 4 Earthquake from really close, but has nowhere near the same affected area as a Level 4 Earthquake, would reasonably be a more like a much smaller earthquake.

For the < 700 km equation, while distance can add Magnitude, it can also subtract magnitude. As an example- feeling the effects from what feels like a Magnitude 4 earthquake, or being shaken, from 1 meter away (as in someone punches the ground right in front of you, and you feel a shake but anyone even a bit farther away does not) would be-

• 4+6.399+1.66*\log((0.001/110)((2\pi)/360)) = −0.8881954272
• 10^(1.5*−0.8881954272+4.8) = 2,935.667461 joules, or Street level.

...Which actually makes sense.

 

[KLOL506]

Huh. Wonder what it means for earthquake feats now, whether they can make a comeback or not.

 

[DontTalkDT]

My question now becomes where did the <60 km and 60 ≤ r < 700 km equations come from, because they don't have a log like the r ≥ 700 km equation did. Earthquake power is logarithmic right?
(I swear I'm not continuously asking for sources to eat up your time- I'm genuinely curious)

The richter scale to energy formula is logarthmic (or, well, exponential). The equation to adjust richter scale with distance aren't. If you combine the adjustment formula with the richter scale to energy formula you against get an logarithmic (/exponential) formula.
The log in the ≥700km version actually has something to do with adjusting for the curvature of Earth IIRC.
The formulae come from this.

 

[KLOL506]

The richter scale to energy formula is logarthmic (or, well, exponential). The equation to adjust richter scale with distance aren't. If you combine the adjustment formula with the richter scale to energy formula you against get an logarithmic (/exponential) formula.
The log in the ≥700km version actually has something to do with adjusting for the curvature of Earth IIRC.
The formulae come from this.

Lemme guess, you used inspect element black magic to get the formulae from here once more, right?

Also what does this mean for localized quakes? Do they get to come back if the radius is big enough? How big is big enough? 50 meters? 100 meters?

 

[DontTalkDT]

Lemme guess, you used inspect element black magic to get the formulae from here once more, right?

Also what does this mean for localized quakes? Do they get to come back if the radius is big enough? How big is big enough? 50 meters? 100 meters?

Huh? No the pdf linked actually just says what the formula is. Well, it says what the formula is in reverse (knowing the energy/magnitude what is the mercalli scale value), but it is easy to invert.

As we agreed in the last thread, the Earthquake just needs to be decently large (or actually called an Earthquake). We didn't agree on a specific radius or anything. All we want to avoid is something like the shacking caused by the usage of heavy machinery being calced to ridiculous levels.

 

[KLOL506]

Huh? No the pdf linked actually just says what the formula is. Well, it says what the formula is in reverse (knowing the energy/magnitude what is the mercalli scale value), but it is easy to invert.

Ah, okay then.

As we agreed in the last thread, the Earthquake just needs to be decently large (or actually called an Earthquake). We didn't agree on a specific radius or anything. All we want to avoid is something like the shaking caused by the usage of heavy machinery being calced to ridiculous levels.

Hmmmmmm, how about situations like this and this? (Context: Connor here uses Bear Might to violently shake Washington's Pyramid while being at the edge- causing parts of the roof to fall off and shaking Washington enough to make him unsteady on his chair, and then after getting inside the pyramid, him using the Bear Might severely destabilizes the pyramid and even causes the wooden scaffoldings to collapse, the pyramid is pretty freakin' big) I know I've asked about this specific AC3 feat already many times but I'd be grateful if my concerns regarding it were alleviated. Would this be considered as decently large or would it fall victim to the "localized area affected" argument?

 

[DontTalkDT]

Hmmmmmm, how about situations like this and this? (Context: Connor here uses Bear Might to violently shake Washington's Pyramid while being at the edge- causing parts of the roof to fall off and shaking Washington enough to make him unsteady on his chair, and then after getting inside the pyramid, him using the Bear Might severely destabilizes the pyramid and even causes the wooden scaffoldings to collapse, the pyramid is pretty freakin' big) I know I've asked about this specific AC3 feat already many times but I'd be grateful if my concerns regarding it were alleviated. Would this be considered as decently large or would it fall victim to the "localized area affected" argument?

So it shakes the entire pyramid? How large is the pyramid? Which level on the Mercalli scale would you say the shacking has for areas at the edge (i.e. far away from the epicenter of the shacking)?

 

[Bobsican]

I recall people disliked Barney the Dinosaur being rated 8-B out of doing magnitude 4 earthquakes just for a few meters, so I guess a minimal would be above that.

 

[KLOL506]

So it shakes the entire pyramid? How large is the pyramid? Which level on the Mercalli scale would you say the shacking has for areas at the edge (i.e. far away from the epicenter of the shacking)?

Yep, it does, and violently at that. Pyramid at its widest according to the in-game map is 164m. Connor shakes it at the entrance, and entrance to center of pyramid I found to be 111 m (So that's his minimum distance of shaking from epicenter). Don't worry, I have the images of the map at hand.

Washington is visibly struggling to hold his tea-cup even when sitting on his throne (While his rooftop starts to fall apart slowly), with everyone around him in the near vicinity being visibly concerned and considerably affected by the shaking, and in the second link once Connor gets inside his Bear Might literally causes wooden scaffoldings to collapse left and right, so at the bare minimum I'd say Scale V-VI.

 

[DontTalkDT]

Yep, it does, and violently at that. Pyramid at its widest according to the in-game map is 164m. Connor shakes it at the entrance, and entrance to center of pyramid I found to be 111 m (So that's his minimum distance of shaking from epicenter). Don't worry, I have the images of the map at hand.

Washington is visibly struggling to hold his tea-cup even when sitting on his throne (While his rooftop starts to fall apart slowly), with everyone around him in the near vicinity being visibly concerned and considerably affected by the shaking, and in the second link once Connor gets inside his Bear Might literally causes wooden scaffoldings to collapse left and right, so at the bare minimum I'd say Scale V-VI.

The scaffolding is closer, though, so it is not a good measure for the mercalli scale at distance.
Anyway, notable shacking of an area over 150m in radius seems large enough for me.

 

[KLOL506]

The scaffolding is closer, though, so it is not a good measure for the mercalli scale at distance.

Connor was also causing scaffoldings further out from him off-screen to collapse as a result. The one in front of him was just one of the many examples we see falling down, as he free-runs his way through the collapsing scaffoldings further and further out.

Anyway, notable shacking of an area over 150m in radius seems large enough for me.

'Kay. Connor is rougly 111 meters from the epicenter of the pyramid tho, at least, when he slams hard at the entrance, but the entire things still shakes as a whole (All the way to the edge I believe.

So should using Richter 4-5 be fine? Or should I just use Richter 4 instead?

 

[DontTalkDT]

I would do two ends and see what the person evaluating the calc likes.

 

[KLOL506]

I would do two ends and see what the person evaluating the calc likes.

'Kay.

 

[DMUA]

I read most of this thread and I'm honestly baffled as to why this is suddenly okay again

Like I'd probably have to properly pull out why this stopped being used but this sorta just got greenlit for... absolutely no reason other than "sure this sounds okay"

 

[KLOL506]

I would do two ends and see what the person evaluating the calc likes.

Old calc used Magnitude 5 BTW.

Here's my version. Which is literally the exact same.

 

[KLOL506]

Old calc used Magnitude 5 BTW.

Here's my version. Which is literally the exact same.

Dark-Carioca and DemonGodMitchAubin accepted my calc.