Earthquake / Tsunami Calcs Revision

[Damage3245]

After a conversation with DontTalkDT in this message wall here, it has been discovered that a method to find the energy of an earthquake from the height of a tsunami is flawed.

The formula currently being used to get the energy of an earthquake from the height of a tsunami is:

Mw1=1.5667ÔêùLog(H)+7.0781

But this formula doesn't calculate the Richter Magnitude of an earthquake, but the moment magnitude. Currently it is being used as the Richter magnitude in calcs such as this Elfen Lied calc and this One Piece calc.

There is apparently a theoretical relationship between moment magnitude and radiated energy, but that there is no actual way to determine the variables necessary to use it.

Either way, the two calcs at least that I have linked above are wrong and need to be removed and revised.

 

[Ugarik]

Well it's not flawd in a sence but does seem extremly weird.

In case of One Piece. Whitebeard needed two tsunamies to destroy Marineford creating a massive earthquake to make them. But the potential energy of those two tsunamies was somewhere around 8-B region. Which basicaly means Whitebeard used a country level attack to create a city block level attack.

 

[Damage3245]

It is both weird and seemingly wrong as the incorrect value is being put into the earthquake calculator currently.

 

[Ricsi-viragosi]

Well it's not flawd in a sence but does seem extremly weird.

In case of One Piece. Whitebeard needed two tsunamies to destroy Marineford creating a massive earthquake to make them. But the potential energy of those two tsunamies was somewhere around 8-B region. Which basicaly means Whitebeard used a country level attack to create a city block level attack.

It could make sense in-verse since sea water would drown or at least weaken almost all characters remotely comparable to him.

But that doesn't change the calc being wrong, as the OP said.

 

[Xulrev]

Well it's not flawd in a sence but does seem extremly weird.
In case of One Piece. Whitebeard needed two tsunamies to destroy Marineford creating a massive earthquake to make them. But the potential energy of those two tsunamies was somewhere around 8-B region. Which basicaly means Whitebeard used a country level attack to create a city block level attack.

This is definitely an enormous logical inconsistency, and would be awkward to hold as correct on a site devoted to seeking truth in such matters.

It could make sense in-verse since sea water would drown or at least weaken almost all characters remotely comparable to him.
That doesn't make sense since Whitebeard created a tsunami large enough to coat the entire island regardless. So that's a self-defeating line of thought.

On the topic of Moment Magnitude, it appears that this is actually the standard scale for seismological authorities. So I'm actually curious why Richter is used at all on-site since Richter seems to be considered fallible.

Generally the OP seems correct in its assertions however, in that it's contradictory to what is standard on-site and applies Moment Magnitude as Richter Magnitude, when they're differently-calculated things.

As such the calcs need re-worked and tossed out for now, blatantly so.

 

[Migue79]

Hello! Author of the calc here writing this wee message on my phone as I am writing this in a hurry.

First and foremost, I apologize for not responding sooner.

I unfortunately missed that part about the magnitude scale used in the equation. But it's okay. I do recall seeing several alternatives in the form of articles to adjust the calculation (i.e. converting Mw to ML, finding Me from Mw to calc radiated energy, possibly the same article as the first one in my calc but applied to the Richter scale, etc.). I'll double check in case I am wrong, though.

Unfortunately, I am extremely busy as of lately, but should be free next week. So expect full collaboration from me when that time comes.

I will say this, though. Moment Magnitude accounts for what the Richter Magnitude measures AND more.

Anywho, I'll be gone now. Later!

 

[DontTalkDT]

On the topic of Moment Magnitude, it appears that this is actually the standard scale for seismological authorities. So I'm actually curious why Richter is used at all on-site since Richter seems to be considered fallible.

Because we have the formulas to calc earthquakes based on richter-scale basically.

The richter scale directly relates to the earthquakes radiated energy, making it very easy to convert from richter scale to AP.

Moment Magnitude is technically a better measure for an earthquakes strength, but to calculate radiated energy from it one apparently needs to know things like the average shear moduli of the rocks that constitute the fault, the static stress drop and the radiated efficiency.

Since we don't really know those things in a fictional story that makes actually using it for our purposes more difficult.

 

[Xulrev]

That makes sense, thanks DT. So essentially, Richter is better than nothing and it's what we can make work, even though it's not the strictly best method of measure.

 

[Damage3245]

Bump.

If a solution isn't found, the current calcs will have to be removed from the profiles they're affecting.

 

[Migue79]

Greetings from the future! (Because I'm now in a different time zone ahead of you kek)

I am now back ready to readjust the calculation. Soooooooo, let's get this started.

I have been doing quite a bit of research and found a few articles relating to scaling Mw to ML.

This is one of them (hopefully the link works).

This article states that there is a relationship between the two as such:

Mw/ML = 0.98 (according to the data sets)

Mw/ML = 2/3 (1 + Fault Aspect Ratio)

Fault aspect ratio can be calced by taking the displacement of the fault (how much the sea floor moved up) and divide it by the length of the crack.

Fortunately, there is some discussion about varying aspect ratios and mentions of lower aspect ratio due to higher earthquake magnitudes.

I have also been looking for another alternatives such as devicing a formula that uses Mw directly to Es (Radiated Energy). Do let me know if you wish to hear about this alternative.

Lastly, I have read in an article that the shallower the earthquake is, the ML magnitude will be very close to the Mw magnitude. I can find it soon if you wish me to do so.

 

[The_Calaca]

Bump. Migue updated his Elfen Lied calc.

 

[Udlmaster]

Might be good to ask DMUA about this.

 

[Migue79]

I have readjusted my calc. Should I post it here or in the Calculation Evaluation forum?

 

[Ricsi-viragosi]

Here, calc evaluation would be for already accepted methods, I think.

 

[Migue79]

I mean, my method was a new one and I posted it there and it got evaluated.

I'll do both I guess.

Here it is anyway (to the bottom where it says UPDATE)

 

[DMUA]

Might be good to ask DMUA about this.

Why do I need to suffer specifically

I still haven't really looked into the specifics of Tsunamis

I probably could right now but Damage and Ugairk seem more on top of it

 

[The_Calaca]

Bump

 

[Udlmaster]

Might be good to ask DMUA about this.

Why do I need to suffer specifically
I still haven't really looked into the specifics of Tsunamis

I probably could right now but Damage and Ugairk seem more on top of it

Because I like to make you suffer


Because you had the Calc blog for Earthquakes.

 

[Damage3245]

Going by the latest comments on the blog post, it looks like the Low End formula is what is preferable here.

 

[Migue79]

Yes. I believe the third method is the best bet here.

The first one conflicts with the theory that the closer to the surface the epicenter of an earthquake is Mw = Me or ML (approximately) and says that the ML > Mw. So, obviously that one's thrown out the window.

The second one, while it is consistent with the theory at hand, requires to make one assumption. Now, don't get me wrong, it's just 1 assumption I am making. However, in my honest opinion, a method that requires zero assumptions is infinitely better than a method that requires even one assumption.

The last method involves data that was processed. That was analyzed. That was, in a matter of speaking, proven. We can justify the method the most easily out of all the 3. This is why I firmly believe the third method is the most sensible option.

Though if you think the mid-end is fine, then okay. That's fine.

 

[Antvasima]

Do any of our instruction pages need to be modified as well?

 

[Damage3245]

I don't think so. This method is new so wouldn't be on any of them I believe.

 

[Migue79]

We COULD make a new page regarding this method specific for Tsunami via Earthquake feats. But I will leave it up to you all, staff & calc group members.

 

[Antvasima]

Maybe we should add a brief extra section to the Earthquake Calculations page?

 

[Migue79]

We could. I'll get a head start on the page/section tomorrow if necessary.

Whatever the decision is, expect my cooperation.

 

[Antvasima]

Thanks.

 

[Migue79]

Bump.

I have now created a blog for the small section to add to the Earthquake Calculations page. Do let me know if any loose ends need to be tied.

 

[Damage3245]

The blog post looks good to me.

 

[The_Calaca]

Agreed. It looks good.

 

[Migue79]

Can this now be implemented?

 

[Antvasima]

I would prefer if DontTalk and Ugarik comment as well.

 

[Spinosaurus75DinosaurFan]

bump

I'm fine with that too, it looks good.

 

[Antvasima]

Is somebody willing to ask DontTalkDT and Ugarik about if they consider the blog draft acceptable to apply?

 

[Migue79]

Bump again. Completely forgot about this.

Spinosaurus asked. And Ugarik confirmed his approval in the blog.

 

[Ugarik]

Well I don't quiet agree with DontTalk. While I agree that height of the tsumanis idealy should be calculated from moment magnitude we can substitude it by much simplier formula as long as its result are somewhat close to the true value.

I'm still against using this method because pothential energy of the tsunami is just a small fraction of the total radiated energy of the earthquake

 

[Migue79]

No no. The aim of the method isn't to measure the PE of the Tsunami.

The method uses the height of the Tsunami to find the magnitude of the earthquake that the character in question caused.

 

[Ugarik]

I understad it. I was trying to say that even if the wave was indeed created by a earthquake PE of the wave is usually what matters in context of the feat.

But if most of the people here don't have a problem with this it should be fine.

 

[The_Calaca]

There's also Liger686 who made a calc with a different method. DMUA seems to have accepted the reasoning, although it should be revised by the CGM Group to be sure.

 

[Migue79]

@Ugarik Ohhhh. You're talking in the context of One Piece. I misunderstood. My bad.

 

[Antvasima]

I have now created a blog for the small section to add to the Earthquake Calculations page. Do let me know if any loose ends need to be tied.

So should this be applied now then?