In this scene, Captain Marvel sends Ultron to the core of Xandar and it causes a shockwave. The core has a diamter of 1244 px and the diameter of the blast is 236 px. The panel itself is 1289 px tall. Now, the outer core has a radius of about 3483 km. Additionally, using the planet curvature method with the core instead of the planet, we'd get:
sqrt(1-(tan(35)*(1244/1289))^2/((tan(35)*(1244/1289))^2+1))*6966=6335.08626714 km
6335086.26714/1244=5092.51307648 m/px
236*5092.51307648=1201833.08605 m
Using the overpressure method, we get:
W=600916.543025^3*((27136*1.37895+8649)^(1/2)/13568-93/13568)^2
W=1.7439258e+13 tons of tnt (Country level)