A disturbance in the force

Hey ALE readers. This isn't my normal day to post anything on here, but I hadn't been paying attention to the news in Japan until I got sucked into an NPR discussion of the recovery this evening. Many things have happened there, at a large scale over the past 3 days. These are the 3 heavy hitters.

1. A tsunami struck the northeast coast 30 minutes after a 8.9 subduction earthquake occurred close by.
2. A recent estimated death toll has topped out at 10,000 people from the combination of these events.
3. Two nuclear reactors at a damaged coastal power plant have exploded, creating unconfirmed fears of large-scale radiation exposure. A 12-mile radius has been evacuated.
   

At the ALE lab, we focus our research on smaller agricultural disturbances, both natural and human, but I think these events are relevant to our work particularly in video 2 below. What we mean by a disturbance is a change in stasis in an environment by plowing, spraying pesticides, introducing pollinator habitat, etc. However, on 11 March a much larger disturbance occurred off the the coast of Japan in the form of an earthquake, creating a series of other ecological disturbances, including massive flooding of harbors, towns and farms. Japan, a very earthquake-prone and earthquake-ready nation, actually gave the phenomenon its name, "tsunami," which means "harbor wave" and now commonly refers to a large volume of water displaced by volcanic or tectonic activity.

The earth is like a chewy candy with a hard shell. The shell rests on molten rock as huge plates (picture 1). Japan is the eastern edge of the Eurasian plate, pushed up out of the Pacific ocean by the Pacific plate in what is called a subduction zone. The edges of these plates can be ripe with activity as the earth settles and adjusts itself, almost like an old house. You will notice from the map where other regions of the world sit on these plates, and how newsworthy seismic activity tends to occur the most along their edges.Subduction earthquakes result when the upper plate "catches" on the lower plate as the lower plate moves beneath it. Over time, the upper plate slowly bends until enough pressure builds and it breaks free. Very quickly, a high volume of water is sent straight up from the sea floor (video 1). Japan experienced the massive tremors from being on the upper plate, in a sort of springboard effect.


The high tsunami waves at sea do not ebb like normal tidal and wind waves, but continue to flow away from the epicenter in reaction to its rapid displacement from the sea floor until all of the displaced water's energy dissipates. This is what causes the continuous rush of flood water that you will see in the next video.


I shutter at the thought of all the grad students whose projects just washed away in those fields, not to mention all the kind grower-collaborators who managed them...

If you would like more information and multi-media I highly suggest this NYT link showing before/after satellite images and this integrated timeline and map of events in Japan which students and press from inside and outside the country have been doing their best to put together with social media where internet access and electricity is available.