Yeah I don't really see what this has to do with those images either. Care to illuminate us? There are massive cracks already under water in the middle of the Atlantic ocean, and all around the Pacific ocean. http://goo.gl/maps/2It9Q As already mentioned there's liquid rock (magma) in there oozing out, and since those are particularly hot spots, the water in contact is both boiling away and reacting to form igneous rock. The first moment that a crack appears, that has water access, will do as you suggest for a while until it meets the magma, and you'll have the beginnings of a new ocean.