Due to this quote we know the distance between the camelot (presumably the gate) and ozy's temple is 100km (which is to small to see on the unmarked map, but it's location is known due to the marked map). As we know the distance between Ozy's kingdom and Camelot to be a 100km we can pixel scale that to figure out the size of the hole/crater.
Scaling it gives us a diameter of 33.5135135135135133324km or 16.7567567567567566662km radius for the crater.
Due to the slight angle we can pixel scale the height of the edges more or less, which will be used as the depth, as such it gives a height/depth of 1.6216216216216216207km.
Due to being completely flat (as the city seems to be at a flat elevation without any drastic changes in the foundation and the other craters had a flat base as well) and the edges of the crater seem to be tightly hugging the walls of camelot, I'm assuming the crater to be a cylinder.
1430.4718962825km 3 or 1430471896282499840cm3 for the volume of the crater.
Two ends being pulv and vaporization, pulv because there's never any traces from the craters Lance creates and vaporization due to the fact the heat from the impacts that create the craters made the area a completely black and scorched wasteland on fire, plus the Lance is capable and is widly know for vaporization.
1430471896282499840cm3 x 214jcc = 306120985804454965760 joules or 73.16467155938 gigaton.
1430471896282499840cm3 x 25700jcc = 36763127734460245888000 joules or 8.78659840689776 teraton.
6-C to 6-B.