azog

I recently learned that the films employed the Angerthas Erebor for the name Azog. I'd have guessed the Angerthas Moria -- I realize Thrór and (I would guess) Nár ultimately hailed from Erebor, but wouldn't Azog know the runic system as found in Moria? Or is there something else I'm not...

Then Azog laughed, and he lifted up his head to let forth a great yell of triumph; but the cry died in his throat. For he saw that all his host in the valley was in a rout, and the Dwarves went this way and that slaying as they would, and those that could excape from them were flying south...