The problem though is that both Zalarek and Emerald Dream were large zones. So it stands to reason that the zone in 11.1 is also going to be large.
In addition, in every source regarding Undermine, nothing is mentioned surrounding the location, it's simply undermine beneath Kezan. Vanilla maps back that up as well, with Undermine essentially being its own entire landmass.
So if Undermine doesn't fill the zone, what else would be adjacent to it?