Bleach- Shikai Ichigo's Black Getsuga.

So what we have here is ichigo's latest feat, were he uses getsuga-tensho on Yhwach and as a by-product destroys the top of the Royal palace (http://www.mangareader.net/bleach/619), the top of the Royal palace is cone shaped so first we need its volume:

Vcone=R*R*3.14*h/3

R=radius of the base circle.

h=height of cone

to get that we need the overall measurements of the royal palace, and since we currently have no way to directly pixelscale its size, we need to consider a few things, first we now that earlier Ichibei knocked Yhwach 1000ri (ri=3930 meters) away from the general vicinity of the palace with his attack Senri Tsūtenshō 

he then did so again to Yhwach almost immediately after, (http://www.mangareader.net/bleach/605/10) (http://www.mangareader.net/bleach/605/12)

and that here he sends him all the way back. (http://www.mangareader.net/bleach/606/16)

however he did so in different directions so we cant overall assume that the distance is 2000 ri, luckily though we can see the angle between Yhwach's "flights" here ( http://www.mangareader.net/bleach/605/15) which to me seems like around 110 degrees, so we have an isosceles with two equal sides with the length of 1000 ri each, and thus each of the non-head angles are equal to 35, so to find length of the base we will draw the hight and use the following:



cos 35= 0.5*a/b

b=1000 ri=3930 km

a=distance from the royal palace

3930*cos35=0.5*a

3219.26=0.5*a

a= 6438.535 Km

now from here we can find the size of the royal palace using the formula here (http://psycnet.apa.org/journals/rev/57/5/314/) which indicates that:

In the same scan, we can see that the width of the royal palace (or the diameters of the base circle) is 11 pixels, and the height of the cone is 6 pixels, so:

Diameter of royal palace=(11/33)*547275.48=182425.16 meters

Height of cone=(6/33)*547275.48=99505.63 meters

Lets calculate:

R=diameter/2=91212.58

Vcone=91212.58*91212.58*3.14*99505,63/3

Vcone=8.664*10^14 m^3

m^3=1000000 cm^3

Vcone=8.664*10^20 cm^3

Now from here there are two possibilities, the most likely is that the cone was pulverized, which for stone is 214.35 joules for centimeter cubed, and the other less likely possibility is because of the smoke in the aftermath of the attack, one might argue the cone roof thingy was vaporized which clocks in 25700 joules of energy per centimeter cubed, so:

8.664*10^20 * 25700=2.22*10^25= 5.32 Petatons of TNT

All Credit of this Calc goes to Illuminati478 of VS Battles Wiki