great theory but i have to agree with ghost. we know that the map surely has to be english due to the name being in the language and the hints from the boards in der riese.
Ascension Island is part of the british empire, therefore english and when studying the island it has a lot of craters. Indicating maybe a meteor landed on ascension island containing a vast amount of element 115.
We know that richtofen wanted to go to area 51 while at der riese because it had vast quantities of the element 115.
So maybe knowing area 51 is in-acesible he sets the teleporters for ascension island where the element 115 is still there from a meteor crash.
The 4 characters then start by the meteor and maybe have to ascend up the volcano to escape the zombies? maybe the first outdoor map (would be good).
The use of this island would also link nicely into the suggestion of the next map being french, again hinted from the boards in der riese. As napolean was exiled to St helena which is next to ascension island.
Just a theory but could be right, never know.