thomas.berubeg
Wandering the World
I think that the idea of having it be a crater was because Braduk the Burning is built around the crater left when Bhall crashed through Erebus during her fall from her vault of holy fire to Agares' vault. This is a massive crater with flames and lava within, but it is not a mountain-like volcano. It is an impact crater that leads to hell itself.
yeah...
the way i see it, Old Bannor Braduk was a city built around a large temple and Palace complex devoted to Bhall and housing her priests and the creme of the Bannor soceity.
when Bhall fell through, i imagine she took with her the center of the city: the temple, the palaces, and all those there (come to think of it, probably most of the bannor nobility and priests, as they would have been nervous and confused by the astral signs.) Wha she left behind was the outer city, the houses, the market places, all but the central Authority.