Satellite Photos of Japan, Before and After the Quake and Tsunami

[Lasareath]

Crazy before and after pics.

Use the slider to see the before and after of each pic

http://www.nytimes.com/interactive/2011/03/13/world/asia/satellite-photos-japan-before-and-after-tsunami.html?hp

[mrbigbluelight]

Excellent link ! Really gives an appreciation for the devestation that occurred.

[starkiller]

Thats pretty incredible and sad at the same time!

[BlueFox]

Generally, after an earthquake we see pictures of toppled buildings, bridges, etc. However, for this 9.0 quake all we see is damage from the tsunami. It is almost as if the earthquake damage is trivial compared to the damage from the tsunami. The destruction is amazing from this thing. I was watching a video yesterday of it, and it just keeps coming. Higher and higher, washing everything away. What a nightmare.

[cheddar]

I think Japan was prepared for the quake, but the tsunami was just worse than their worst expectations. I think the nuke plant was built to take 5 meters and they got like 6. A 'model tsunami' town on the coast further north had a sea wall to take 10 meters and it got hit with something around 14. It was the third time in around a century that this particular town has been wiped off the map by a tsunami. Just shows you what eventually happens when the best human engineering meets the extremes of nature. Yes, very sad for the Japanese people. But the engineering that went into preparing Japan for an earthquake and tsunami was still among the best the world has to offer.

[maximillian]

^ I don't know if any wall would really help. It's not like the wall would have to stop a typical huge wave. This Tsunami was a massive amount of water that "gradually" (in a matter of minutes) rolled in. There's just so much water that it has to go somewhere, and that means it will go even over tall walls.

Watch this video. It is truly scary.

http://www.liveleak.com/view?i=3a7_1301163352

[cheddar]

^ I don't know if any wall would really help. It's not like the wall would have to stop a typical huge wave. This Tsunami was a massive amount of water that "gradually" (in a matter of minutes) rolled in. There's just so much water that it has to go somewhere, and that means it will go even over tall walls.


This was NOT a typical seawall. It was specifically built along the entire coast of the town to prevent what happened twice before...a big tsunami wiping out most of the town.

And tsunamis don't move water from point a to point b, they move energy. If I understand it correctly, tsunamis aren't moving a drop of water from the earthquake center to the coast, they transfer the energy from the quake along the water in a wave. It's this energy that lifts the water up over the wall on the far away coast. And only if it breaches the height of the wall, will the water then flow inland and be a problem.

[maximillian]

And tsunamis don't move water from point a to point b, they move energy. If I understand it correctly, tsunamis aren't moving a drop of water from the earthquake center to the coast, they transfer the energy from the quake along the water in a wave. It's this energy that lifts the water up over the wall on the far away coast. And only if it breaches the height of the wall, will the water then flow inland and be a problem.

That's true up until the energy wave runs out of medium to propagate through. Then the energy dumps the massive amount of water ashore. Whether or not it rolls in or lifts in as a wave depends on the terrain.

[cheddar]

That's true up until the energy wave runs out of medium to propagate through. Then the energy dumps the massive amount of water ashore. Whether or not it rolls in or lifts in as a wave depends on the terrain.

The 'terrain' is that massive seawall. It will lift up until it's maximum height. Just like if you cracked a whip, the end of the whip moves in line with the initial displacement of your hand (your hand and the handle of the whip didn't slam into the air at the end of the whip to make the crack, the end of the whip did). So as long as the end of the whip tops out below the wall, the water just moves up. If it goes over, all that water pours in. That wall would have worked as designed if the tsunami hadn't lifted the water over the wall. If the tsunami was really 14 meters high, then if the wall had been above that, it would have stopped it.

[maximillian]

I think we're basically trying to say the same thing. The engineers made an assumption of how much water they would have to deal with and unfortunately the assumption wasn't enough for this event.

[cheddar]

I think we're basically trying to say the same thing. The engineers made an assumption of how much water they would have to deal with and unfortunately the assumption wasn't enough for this event.

If you had said this instead of this:


^ I don't know if any wall would really help.

Then yes, you would have summarized my point and we would agree completely. :biggrin:

[bobman1235]

I don't think any reasonable person could justify a 14 meter wall. Do you have any idea how tall that is? There becomes a point where you're protecting against something whose infinitesimal likelihood is far less than the astronomical cost.

[cheddar]

I think the original 10 meter high sea wall probably had an astronomical cost. They just didn't build it 50% higher because they didn't think they'd get one 14 meters high. It was supposed to be some sort of 'model' tsunami town. Maybe something they were trying out as opposed to something every single town on the coast would get.

[cheddar]

Here it is:

http://www.cnn.com/video/?/video/world/2011/03/18/dnt.model.town.gone.nhk

Took them 30 years to build and stretches for several kilometers. Looks like it's almost two sets of walls joined in the center like an 'X'.