[LargoLasskhyfv]

Depending on the scale and speed it probably would register as something "off", but not necessarily dangerous. As in out-of-context, does not compute. I mean, just look at the videos of the tsunami in Thailand, 26 December, 2004. Most don't get it. How should they, if they have never experienced it before?

Maybe OT, but to demonstrate a similar thing I once experienced: Been bicycling in the forest like ever so often, and something was off. Stopped. Thought someone suddenly built a large, long wall or building there within a few days, because it wasn't there before. Went about 100 to 150 meters into the forest to investigate what it was. A massive wall of whitegrey smoke, with many nests of flames between 50cm and one meter high. Didn't recognize it as such until I saw the flames shining through. Really thought of it as a wall until then.