Hi there, Chronicles of Elyria will be using something called SpatialOS (along with Soulbound Studios own server side software) which will use Google Cloud Compute servers to scale.
I'm pretty sure when you spin one of these up you choose a zone for it to be run from. But it's the Google platform that ultimately decides what physical machines the game world will use.
But for all intents and purposes each of the four instances will be in those zones. We just can't pin down exactly what data centres in what city or state the game will be running at at any given moment.
The great thing about using the big 3 (or more) cloud providers is that even if they lose an entire data centre, our game should carry on running.