This design for Khazad-dûm includes two bursts of fiery light juxtaposed against each other, one up in the sky and the other in the depths of the earth. The wielder of the flame of Anor pitted against the flame of Udûn; the brilliant light of the Sun above mirroring the lower light of Durin's Bain.
The heights of the Mountains of Moria above mirror the extreme depths dug by the mithril-mining dwarves, which disturbed the Balrog, and eventually led to the destruction of the wonderful city of Khazad-dum, and it taking on a new name: Moria, the Black Pit.
The runes in the middle of the design spell out "Khazad-dûm."