With cameras of all types having become ubiquitous, it was only a matter of time before images were taken of a tsunami in progress that for the first time really showed why these events were so catastrophic.

There were numerous photos and videos of the December 2004 tsunami in the Indian Ocean, and many showed the horrific scale of the devastation and even something of the power of a great tsunami. However, none that I have seen have showed what at least one truly chilling photograph from Japan has showed: what a tsunami really is.

Many of the pictures taken of the 2004 tsunami and the one that has just struck Japan show the  monstrous forces of the water, pushing boats, vehicles, houses, buildings, almost anything in its path. However, there is one photo of the tsunami from that was caught from a distance and at an elevated angle that clarifies what is really happening.



A normal wave has a peak, behind which is a trough. That wave crashes ashore and water runs up that shore, but the water behind it is lower than the wave, and the water recedes.

This photo shows something else. The bottom half of the photo shows houses being moved by the water which is higher than many of the roofs. About a third of the way down from the top of the photo the water is seen breaking through a line of trees, and the water is flowing downward. At the very top of the photo is the crest of the wave and the curvature indicating the water falling in front of it. Notice there is no trough behind it. The sea itself has become higher, much higher, than the land, and as such, the tsunami is not running up onto the land but falling down on it.