They had a physicist on Maine Public Radio and they were saying that they don't actually know the cause and that they're extremely rare, but not unheard of. The issue is that they are so rare that they've not yet been given much study. They are hoping to catch the current conditions and then examine eddies and the terrain beneath it, and maybe learn more about it.
I can only imagine how difficult it is to measure these things. I'd be so worried about messing up the current so as to throw the whole thing off. I hope they get good science stuff done with this thing.
If things align properly, I'll go down tomorrow and have a peak at it.
Believe it or not, fluid dynamics is still not nearly as well understood as people may think. So, this may be something of greater interest, but it's way too early to suggest that it is.
That's super cool, although I might freak out if my town had one of those.