Haven't done a calculation in a good long while, so I figured something small wouldn't hurt to get back into the flow.

It's back to the Pokemon videogames, except this time I'm not exploring either a certain species or a particular feat by an individual, but rather an entire technique's mechanics.

Specifically, the move Earth Power.

The most recent description of the move is:

"The user makes the ground under the target erupt with power. It may also lower the target's Sp. Def."

The bolded portion of the statement being the key factor involved. More or less, the technique seems to involve the user triggering an eruption of lava directly beneath the opponent, from magma reservoirs deep underground (though only in the videogames; the anime depicts it as a generic energy burst from the ground). Recently, I came across this article, demonstrating a new minimal depth range for volcanic reservoirs between 2-6 kilometres.

So we have a minimal "height" of the lava flow upwards, but what about width?

I chose to use the torso length of probably the longest non-Legendary user of Earth Power, Camerupt to equate to the width of the lava flow. Not too low-end, not too high-end at the same time. The overall height of a specimen is 1.9 metres.

Spoiler:

Going to treat the resulting volume as a cylinder: I know it doesn't mesh particularly well with the visuals being not perfectly cylindrical in shape, but I'm sticking with this unless I get a better option pointed out to me.

Volume of a cylinder =

Going to use a low-end and a high-end estimate, with using the minimum and maximum presented factors respectively.

Low-End

3.14*0.72*0.72*2000 = 3255.55 m^3

For determining lava density to obtain the necessary mass of matter, I'll be using the density figure of basalt, as it is the igneous rock type most commonly associated with being the by-product of surface magma cooling. So 2800 - 3000 kg/m^3.

3255.55*2800 = 9,115,540 kg of lava travelling through to the surface.

As the final result will be a kinetic energy equation, I'll also need a velocity for the lava surge. Going back to the technique sequence of Earth Power, it says that the entire event occurs in a duration of 10 seconds. Assuming that the lava flow travel is taken into account in the pre-visual performance, I'll say that it took 5 seconds (first half of the clip features no lava eruption effect) for the feat to take place. With the 2 km distance, that'll be 400 m/s.

(0.5)*9115540*400*400 = 729243200000 joules or 174.29 tons of TNT equivalent.

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That's the low-end calculation (2 km depth, 2.8 g/cm^3 density).

High-end calculation will use the 6 kilometre depth referenced in the National Geographic article and the 3 g/cm^3 density of basalt.

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High-End

3.14*0.72*0.72*6000 = 9766.66 m^3

9766.66*3000 = 29,299,980 kg of lava.

High-end velocity is now 1200 m/s (6000/5 = 1200).

(0.5)*29299980*1200*1200 = 21095985600000 joules or 5.04 kilotons of TNT equivalent.

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Interesting results. Pretty extensive range of the multi-cityblock busting area before just headbutting the minimum output for town-busting level. Most decently powerful fully evolved, final-stage non-Legendary Pokemon (think Whiscash's 405 ton tremors, Charizard's 7.20 kiloton ice-melter, Ampharos's potentially kiloton-scale illumination, even Gigalith's 305 - 977 kiloton mountain-busting) are roughly within that same broad spectrum of firepower, so there should be little issue with these results in terms of in-verse impression. But there may be grievances with my assumptions or calculation mechanics, so feel free to voice those out.

All Pokemon which can learn this technique naturally (though technically even TM, breeding or Move Tutor methods should extend that possibility of calc application, I'm only going to argue this calc on the grounds of those who can actually learn this move from scratch) at least should be able to fall somewhere in that range. A list can be seen here.

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Earth Power Output: 174 tons - 5.04 kilotons of TNT equivalent.