What part of Japan is this?
Same video appears on BBC ...
http://www.bbc.co.uk/news/world-asia-pacific-12722026
"Footage has emerged of Friday's tsunami sweeping through Kesennuma City in Miyagi Prefecture, north-eastern Japan."
Video of tsunami in Japan
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Re: Video of tsunami in Japan
#42I wonder if an artificial tsunami of the same scale can be achieved my setting off a nuclear bomb underwater? This seems to be more damaging (infrastructure-wise) than a direct nuke hit.
It's been tried (kinda). Doesn't really work apparently.
Re: Video of tsunami in Japan
#43other day friend quipped "Japanese are so smart designing quake proof bdgs". seems they forgot the tsunami thing after.
They didn't forget - a Tsunami is a block of water a meter high and several km deep moving at 800km/h. That's a few BILLION tons of water moving at the speed of a jet aircraft - try designing against that.
Important first correction. The wave moves at that speed. The water itself does not. It mostly bobs up and down slightly.
Important second correction. The height of the tsunami when it hits shore is not the height of the tsunami when it is out at sea. All waves, tsunamis included, rise up when the bottom of the water starts to compress the bottom of the wave, compressing its energy into a smaller volume.
With these corrections, a tsunami out at sea is a wave a few cm high moving at 800 km/h with the water barely moving, but with the whole water column moving. It is therefore entirely conceivable that a well-built dike could withstand such a wave.
Obviously such dikes were not in place this time, but the feasibility of building them has been investigated. By Japanese scientists no less. See http://www.pwri.go.jp/eng/ujnr/joint/37/paper/13kato.pdf for one paper on the topic.
Re: Video of tsunami in Japan
#44Earlier quoted context omitted.
It's because the tsunami only becomes visible when it hits your harbors. They used to be called "tidal waves," but the term is inaccurate — that's why it isn't used anymore. They're not like normal waves out at sea, and they have nothing to do with the tides. The fact that it "looks like a big surge side rolling" in does not actually make it tidal.
Did you know Cotton Candy isn't made from cotton?
That doesn't make it any more valid to call it a tidal wave. I would think someone on HN would be happy that a misnomer is no longer being used.
Re: Video of tsunami in Japan
#45The beginning of the flood looks innocuous enough, but it keeps on coming...
Re: Video of tsunami in Japan
#46Earlier quoted context omitted.
Not really getting the "harbor" connection. And it still looks like a big surge tide rolling in.
It only becomes a visible problem in harbours (or otherwise in shallow waters). It looks like a tidal wave in the sense that it's a lot of water moving in a given direction. The mechanism causing it is not the same at all, so the name tidal wave is misleading.
As an example a friend of mine was on a boat during the massive 2004 tsunami, but since he was a few miles off the coast where the water was deep he didn't even notice the tsunami sweeping under his boat. Once it hit land it did massive damage.
Re: Video of tsunami in Japan
#47Opera displays a Blank Page, Chrome attempts to play the video with no controls and Firefox tries do download the mp4 file. What on earth is going on here? EDIT: it was just taking too damn long. Could be my connection, though.
In Chrome I get controls when I mouseover the video (11.0.696.3 on Mac).
On Windows Chrome does not give you controls, but you can right click to pause/unpause it at least.
Re: Video of tsunami in Japan
#48I wonder if an artificial tsunami of the same scale can be achieved my setting off a nuclear bomb underwater? This seems to be more damaging (infrastructure-wise) than a direct nuke hit.
According to wikipedia scale an 8.8 magnitude earthquake has approximately the same energy release as a 288 megaton nuke. Since the largest nuclear bomb ever was 100 megaton and a 35km radius for the zone of total destruction, direct bombing is almost certainly more damaging.
Re: Video of tsunami in Japan
#49Re: Video of tsunami in Japan
#50I like how the water level rises from the beginning to the end, at the start there's just a few cars moving a little and you're like "this isn't so bad", and then at the end water is gushing in with cars and buildings rolling around in a cacophony of madness, even the camera man has retreated to well above water level at this point.