Merged 8.8 quake in Sendai, Japan

[Belz...]

And people from 50 miles around don't have to evacuate when a coal plant catches on fire.

I hope you don't drive a car. Those things are deathtraps when you get into an accident with a semi.

 

[William Parcher]

The question asked was, I think, about eyeballing the height of the crest of wave(s) above the rest of the visual water and comparing that to the height of buildings.

This is the wall of water I have been asking about. Of course this illustration shows a wall of water much higher than 13 meters, but it could be imagined as being that height.

Did Japan experience one of these things that was 13 meters?

 

[Rolfe]

The picture shows a breaking wave. Most of the wave seen in the videos wasn't breaking.

Rolfe.

 

[William Parcher]

The video I linked in post 1868 shows incoming waves which are in a state of continual break. Are any of those a 13 meter wall?

 

[NoahFence]

I think we're getting confused between a Tsunami and a Tidal Wave.

If I can recall, a tidal wave is a singular event, while a tsunami has multiple waves associated with it?

I suppose the best example would be Lituya Bay in Alaska, where a landslide caused a tidal wave documented at over 1,700' in 1958.


Taller than the Empire State Building

Of course I could be completely wrong and both are the same.

 

[Belz...]

I suppose the best example would be Lituya Bay in Alaska, where a landslide caused a tidal wave documented at over 1,700' in 1958.

What's awesome about Lituya Bay is that someone was actually there to hear and see the whole event, and surf the damn thing too.

 

[CompusMentus]

I think we're getting confused between a Tsunami and a Tidal Wave.

If I can recall, a tidal wave is a singular event, while a tsunami has multiple waves associated with it?

While you may be right about tsunami being associated with multiple waves, I think the term "tidal wave" is just an anglisised term for the same type of event. But, as the word "tidal" is more associated with the effects of gravity upon large bodies of water, it has become discredited as a correct name for the phenomena.

ETA Good, succinct description of tsunami HERE (Farlex Dictionary)

Compus

 

[jimbob]

I've always assumed that a tidal wave is literally what the Severn Bore is.

 

[Apathia]

All these tsunami videos have been instructive for me (as well as frightening).
It's obvious that the usual tsunami depiction as a wall of water comming at you is not the reality. There is a huge swell with accompaning waves that rushes inland gaining height as it goes.
That's why the 13 meter wall of breaking wave doesn't make an apperance.

 

[Puppycow]

This is the wall of water I have been asking about. Of course this illustration shows a wall of water much higher than 13 meters, but it could be imagined as being that height.

Did Japan experience one of these things that was 13 meters?

A tsunami caused by an earthquake won't look like that. One caused by a meteor mght. Look up megatsunami on wikipedia.

 

[r-j]

A really powerful earthquake, right off the coast, couldn't it cause a wave that looked something like that?

 

[Puppycow]

A really powerful earthquake, right off the coast, couldn't it cause a wave that looked something like that?

Not according to what I've read. It might depend on the slope of the ground though. It can be really tall, and have lots of water, but I don't think it would look like that picture.

http://en.wikipedia.org/wiki/Megatsunami

Megatsunamis can be caused by giant landslides and asteroid impacts. Underwater earthquakes or volcanic eruptions do not normally generate such large tsunamis, but landslides next to bodies of water resulting from earthquakes do, since they cause a massive amount of displacement.

 

[celestrin]

This is the wall of water I have been asking about. Of course this illustration shows a wall of water much higher than 13 meters, but it could be imagined as being that height.

Did Japan experience one of these things that was 13 meters?

Would you settle for 6-10m ones?
http://www.youtube.com/watch?feature=player_detailpage&v=-OaCS31OgK4#t=15s
http://www.youtube.com/watch?v=23Q4TBf_FKY&feature=player_detailpage#t=60s

As the wave breaks, it lasts more than a second for the water to fall down. Assuming that the video is not in slow motion, that would make it more than 5m high, would it not? And also about 11m for 1.5s freefall.

Besides, what are you even trying to say? The video you had linked to, also shows those buildings at Rikuzentakata that get destroyed. Those were 2km (1.25 miles) inland at an elevation of about 5-8m. Would you really expect a tsunami with 13m height to reach there as a wall of water without breaking up or losing height?

There's also Ofunato.
http://www3.nhk.or.jp/daily/english/30_03.html

They found fishing equipment scattered on the high cliff of the city's Ryori Bay and have determined the tsunami reached as high as 29.6 meters.

That's run up height, not a 30m wall.

The video I linked in post 1868 shows incoming waves which are in a state of continual break. Are any of those a 13 meter wall?

How can you tell they're not 13m high? Or is it the wall-like-lessness^TM that you're complaining about? The ones, that aren't breaking, aren't vertical enough?

A really powerful earthquake, right off the coast, couldn't it cause a wave that looked something like that?

Asteroids and megatsunamis were mentioned, but this earthquake lasted for 2 minutes. If similar energy was released in a shorter time frame, the tsunami could've probably been higher. It most likely still wouldn't match the illustration, though...

 

[Rolfe]

I think I remember seeing (on TV) a version of the Rikuzentakata wave that lasted longer than the version on the clips we've linked to. Does anyone know if such a version is available online?

Rolfe.

 

[celestrin]

I think I remember seeing (on TV) a version of the Rikuzentakata wave that lasted longer than the version on the clips we've linked to. Does anyone know if such a version is available online?

I don't remember seeing a longer version of Rikuzentakata destruction, but it's all starting to conflate for me. I've been following this since the beginning, trying to compile videos and images into Google Earth, finding the exact locations where the shots were taken from, but I've lost it all yesterday. Note: don't trust google earth to keep your "My places" data uncompromised...

I do remember another video of the scene, taken from essentially the same place, but after the waters went away. There was just a winding road in the distance and two hollow concrete blocks, two stories high, sitting in the midst of debris. Not unlike some giant, gray, upturned Legos with some small holes on the side, where windows used to be.

If I come upon anything as I rebuild my data, I'll let you know...

 

[Rolfe]

It's possible that it only seemed longer the first time I saw it! It was the first of the tsunami videos to be shown in news broadcasts here. I don't know why it cuts off when it does, as the cameraman seems to be on a safe vantage point on a hill overlooking the town.

Rolfe.

 

[jayh]

deleted. misunderstood earlier post

 

[Puppycow]

Anger and abandonment in a Japanese nuclear ghost town

Looks like this town (Minamisoma) was spared the tsunami but its residents have had to flee because of the nuclear crisis. A few stubborn people are staying though. It's in that 20-30 km no-man's land.

 

[gumboot]

I've now seen dozens and dozens of these videos including ones that show the tsunami waves approaching and reaching the shoreline and bay inlets. I've never seen a wave that looked like it was 13 meters high.

The floor of a building is about 3 meters, so a 13 meter wave is a bit taller than 4 floors (stories). That is indeed a big ass wall of water coming.

But what I have seen are considerably smaller waves carrying an immense quantity of water (very wide not tall). I would say that this tsunami brought enormous quantity of water but not any wave constituting "a wall of water".

That's not how a Tsunami works. Think a Tidal Wave. When you have a beach with a 3m high tide, at high tide does a 3m high wall of water just suddenly come rolling in and wipe out the beach?

A Tsunami moves in gradually. The "height" you hear being referred to is the maximum height of inundation above sea level, and might occur several minutes after the wave initially makes land.

 

[gumboot]

The height of the wave was an interesting point. We're given to understand that a tsunami wave is relatively low and innocuous out at sea, and only gains its height as it approaches the coast. However in these clips, the one that showed the sheer cliff of water was actually the one taken from the deck of the ship out at sea. Possibly because there wasn't anything else around to distract from the scale.

"Out at sea" is, of course, relative. The eastern coast of Japan is on a continental shelf - you have to go about 50 miles off shore at Sendai before you get into water 600ft deep, for example. At 20 miles off shore it's only about 150ft deep.

By contrast the Japan Trench, where the earthquake occurred (and Tsunami was generated) is up to 27,000ft deep in places.

For a wave that big (remember, while regular waves only involve energy transfer on the surface, a Tsunami can reach right to the sea floor) even 600ft water is phenomenally shallow.