Boy oh boy here we are again.
For some reason people just concentrated on toppling mountains and stuff and completley forgot about the myth the legend Tyranitar and his absolutely MASSIVE feat.
Tyranitar is very consistently shown as a pokemon who rearranges the terrain to a point where maps have to be redrawn to keep up with it. It causes mountains crumble and rivers to disappear. But here's his biggest feat:
from the Pokemon Black 2, White 2 and Shield pokedex:
"The quakes caused when it walks make even great mountains crumble and change the surrounding terrain."
Now here's the question, what magnitude to we use and what size should we use for mountains?
Let's get down to magnitude first. We gotta get mercalli scale.
So...the earthquake wiped out a mountain...that is definitely not your average earthquake, but earthquakes beyond 9.5/9.6 are not allowed. F.
I believe that using 9.5 is the BEST OPTION because this earthquake is incomparable with an average mag 9 one. The Chilean earthquake wiped out cities and flooded everything, they say people saw underground water coming onto the surface. Problem is, this is not even close to wiping out a "great" mountain. So i believe that 9.5 will be the best option for this calc.
The problem begins from now on.
What is a great mountain?
Now one would say "ahyuck just use 600 meters like everyone else does in mountain calcs"...no i don't think i will. They are stated to be great mountains for a reason, this isn't your run of the mill mountain damaging feat. Considering this specification in i will try to use some sizes i've seen before and i will try to base them on the locations.
Now the first one is obvious. Pokemon is a japanese game, thus the great mountain standard for japan would be somewhere around 3000 meters i presume. Problem is, the first time we see this entry is when we are located in america and idk what to do here.
To be honest i think i will just go with 3000. Unova is based on new york city, rather than the entire state and thus it barely has any mountains that i can use. I know the state has mountains but neither do they appear in the same areas as the game, nor are they big enough to be considered great mountains. The entry re-appears in Shield but bruh, not a single mountain in UK has the potential to be called great, the tallest mountain there is just 1.5x bigger than the bare minimum needed to be even considered a mountain.
So as per recommendation, i have used 2.0802km as the radius.
And thus we have mountains and their size... but what is the point of their size if the mountain crumbling would give bad results? Simple, i'll be calculating the earthquake itself.
We need the size of the mountain to get the distance covered by the earthquake and thus i am going to assume that Tyranitar is standing right in front of the mountain and the mountain itself is an equilateral cone.
Considering the fact that he is standing in front of the mountain, the height of the mountain would be equal to its diameter and the diameter of the mountain will be the radius of the earthquake.
let's go.
9.5+(0.0238*2.0802)=9.54950876 on the richter scale
10^((1.5*9.54950876)+4.8)= 1.3312608e+19 joules
1.3312608e+19 is 3181789674.9521989822 tons of tnt which is 3.181 gigatons of TNT or High 7-A Large Mountain level
Now for my next trick i will use a low ball. Why a low ball? cause people really like low balls.
For the maximum low ball calc i will use magnitude 9 as a precaution. This is the lowest of the balls as no way in 100 mil years will a mag 9 destroy a great mountain and thus this is basically just for show. Pay attention to the normal calc, not this one please.
9+(0.0238*2.0802)=9.04950876 on the richter scale
10^((1.5*9.04950876)+4.8)= 2.3673536e+18 joules
2.3673536e+18 is 565811089.86615681648 tons of TNT or 565.81 Megatons of TNT, 7-A, Mountain level
As you can see even the lowest variant of the mountain busting earthquake is already damn good. I believe that the 3.1 gigaton feat is more accurate than the 565 mt one as no mag 9 earthquake is strong enough to take down a mountain.