Engineering360: "Watch: Rectangular Icebergs Spotted by NASA Crew"

I've read several articles about this rectangular iceberg. They say that it's much wider than it is tall, but so far none has hinted at why it's broken at right angles. It looks far too perfect to be a fluke.

I have a private theory that the ice fractures in shear stress, and if tension or compression stress were applied to the ice, then the direction of maximum shear stress would be at +/- 45 degrees of the applied stress and thus at right angles, but that's just a guess.

(Mohr's Circle)

Anybody else have any ideas?

Must be Alien's !