Just a simple explosion calc.
Building: 14 px/4.3 meters
Width of Pig City (assuming it hit the entirety, since it reached up to the entrence which is on the other side): 963 px/295.778571429 meters (147.889285714 meters for the radius)
147.889285714^3*((27136*1.37895+8649)^(1/2)/13568-93/13568)^2 is 259.953488151 tons, or Multi-City Block Level.
Pretty much a downgrade if I do say so myself.