The first zone of Eureka will be released in 4.25 and is called Eureka-Anemos. Anemos means wind in Greek. But, more interestingly, Wind is the element by which the First Calamity occurred.The Forbidden Land of Eureka is an unexplored, untamed wild where the very elements are constantly in flux. While exploring Eureka and growing in strength, players will have the opportunity to obtain and enhance Eureka gear and weapons.
Now look at this screencapIt was not until the advent of the Sixth Umbral Era that, by the process of elimination, scholars were able to declare with certainty that the elemental calamity which ushered in the First Umbral Era was indeed connected in some way with wind—possibly in the form of terrible hurricanes, tempests, or tornadoes.
Trees are peeled back and we can see a tornado in the background.
So this brings me to my hypothesis: what if Eureka is a land that is a composite of the focal points/origin points of each era's Calamity? If so, we should see ruins in each new zone that's affiliated with the prevailing civilization's architecture. It seems this zone might be plucked out of space/time, maybe due to the overwhelming elemental energies associated with it, idk. So Anemos would reflect the what Hydaelyn looked like during that Calamity.
If my hypothesis is correct, Eureka should look like:
First zone: Eureka-Anemos (wind)
Second zone: Eureka-Ionos (lightning)
Third zone: Eureka-Pyros (fire)
Fourth zone: Eureka-Geos (earth)
Fifth zone: Eureka-Cryos (ice)
Sixth zone: Eureka-Hydros (water)