Earthquake should have the Starfall radius. I mean... Earthquakes can make tremble gigantic zones in real life...
In my opinion de best idea is the toggable one, constantly draining maelstrom while active, that way you can replace it at will. It would also match better the fantasy, it feels weird to create several EQ at the very same place.
But I believe they can't do it work because none of the toggable abilities in game are targetted but built around the player.