[Springfield Reformer]

My wife had an interesting theory. If you suddenly pop up the North American plate, you might get a cavity or two below that water could drain into. The other theory is that the crutal motion that produced the tsunami also created large turbulence with crosscurrents, not unlike tornado formation, hence a funnel. I like the cavity theory because it’s scarier, but the turbulence theory is probably correct.

[fso301]

My wife had an interesting theory. If you suddenly pop up the North American plate, you might get a cavity or two below that water could drain into. The other theory is that the crutal motion that produced the tsunami also created large turbulence with crosscurrents, not unlike tornado formation, hence a funnel. I like the cavity theory because it’s scarier, but the turbulence theory is probably correct.

It's called an eddy. It's caused when the main current goes one way but something causes a portion to peel off and go the other way. In this case, the something was structures cropped from the photo.

[TXnMA]

If you look at the video of that vortex, you'll see that it formed between two breakwaters that were far apart on the landward end and close together on the seaward end. It also formed when water from earlier waves was draining out at the same time that water from new waves was coming in.

Sounds like a good vortex generator to me -- especially if the incoming waves entered the narrow opening at an angle...