Merged 8.8 quake in Sendai, Japan

[The_Fire]

christ. One of the nuclear reactors have caught fire.....

 

[UnrepentantSinner]

Thanks.

Pretty soon I'm going to have to decide whether to start walking home or wait for the trains, but the aftershocks are continuing so I think the trains might not be running for the rest of the day. They tend to play it safe with them.

I see you're logged off. I hope were able to find a way home tonight or at least are able to hole up in your office until the morning.

Does the wave amplitude get bigger the further from its point of origin (as one would expect), making the wave higher, or are there other factors that affect the height of the tsunami wave as it travels?

This is just awful.

Depends on how much further you're referring. Obviously when you get a significant distance away friction will dissipate the strength and with it the amplitude. I heard a caller on the radio last hour say in Portland the local station was predicting a 1-5 ft. wave as opposed to the strong offshort currents (I figure they were talking about riptides) expected earlier.

 

[23_Tauri]

IDepends one how much further you're referring. Obviously when you get a significant distance away friction will dissipate the strength and with it the amplitude. I heard a caller on the radio last hour say in Portland the local station was predicting a 1-5 ft. wave as opposed to the strong offshort currents (I figure they were talking about riptides) expected earlier.

Ok, that's better news, and the predicted height at Taiwan is much less than in Japan. So fingers crossed.

 

[The_Fire]

christ. One of the nuclear reactors have caught fire.....

ETA: Its in Onagawa (province; Miyagi)

 

[gumboot]

Does the wave amplitude get bigger the further from its point of origin (as one would expect), making the wave higher, or are there other factors that affect the height of the tsunami wave as it travels?

Tsunamis have low wave height until they hit land - in the open ocean they're actually typically smaller than regular waves. There's no real rule as to waves getting bigger or smaller further away. As a broad general rule the waves will be bigger closer to the epicenter and dissipate at greater distances as the energy spreads across more ocean.

However local specifics can greatly influence the impact. For example Bangladesh was quite close to the 2004 Boxing Day Tsunami, and is very low-lying, but escaped relatively unscathed, with only two deaths. Somalia, which was at a vastly greater distance, suffered as many as 289 deaths and was hit much harder. Part of that is because the quake rupture was North-South which means the majority of energy was released East-West. Part was also because of the physics of waterways between the epicenter and various spots.

I'd be surprised if this earthquake caused significant Tsunami issues beyond Japan itself. The 2004 Tsunami hit peak localised heights potentially as great as 30m, which is substantially higher than reported from this quake.

 

[Last of the Fraggles]

This looks horrendous. Got quite a few friends in Japan and neighbouring countries. Hope they are all safe and sound.

This sounds horribly ominous: The Red Cross warns that the tsunami wave caused by the quake is currently higher than some Pacific islands and "could go right over them".

 

[Soapy Sam]

I'm a bit hazy about the timezones involved, but surely any tsunami ought to be getting near New Guinea soon? It will be dark over most of the Pacific .

I know after the Christmas Quake they improved warning systems around much of the Pacific.

BBC is saying the nuclear plants nearest the quake all shut down automatically, which is excellent news.
USGS tsunami advisory page.
http://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usc0001xgp/#tsunami

The fire in Miyagi is a refinery. I heard no reports of a fire in a nuclear plant.

 

[The_Fire]

Ok, that's better news, and the predicted height at Taiwan is much less than in Japan. So fingers crossed.

Yes, but you still have to factor in the speed. At 500 km/h, its like getting hit with a sandblaster up close. At that speed it will be extremely destructive.

 

[23_Tauri]

christ. One of the nuclear reactors have caught fire.....

Japanese PM says there's no radiation leak. Proof if one needed that the Japanese build their nuclear power stations well, to withstand earthquakes.

Thanks for the info on tsunami physics, gumboot.

 

[gumboot]

Taiwan: Estimated height of wave: 0,5 - 2 meters (is this correct?!) at a speed of 500 km/h

500km/h will be the open water speed (that's actually pretty slow for a Tsunami). As the wave reaches shallow water it slows dramatically to more like 30-80km/h (still plenty fast to do serious damage and impossible to outrun).

 

[The_Fire]

Japanese PM says there's no radiation leak. Proof if one needed that the Japanese build their nuclear power stations well, to withstand earthquakes.

PHew. I hear "Fire" and "nuclear reactor" in the same sentence and I flashback to Chernobyl. This is good to hear.

 

[Soapy Sam]

This looks horrendous. Got quite a few friends in Japan and neighbouring countries. Hope they are all safe and sound.

This sounds horribly ominous: The Red Cross warns that the tsunami wave caused by the quake is currently higher than some Pacific islands and "could go right over them".

As someone said, a tsunami may be undetectable at sea. It becomes a threat as it enters shallow water and "piles up". Hell of a lot of energy.

In this case, I'm reassured to some extent by the (relatively) small waves hitting Japan itself, but local damage varies with the shape of the coast.

 

[23_Tauri]

PHew. I hear "Fire" and "nuclear reactor" in the same sentence and I flashback to Chernobyl. This is good to hear.

I haven't seen anything confirming a fire at any of the nuclear power stations, although there is a large fire at an oil refinery.

 

[Rolfe]

I wonder if the thing to do if you're on an island in the Pacific is to get in a boat and get as far offshore as possible? I seem to recall that boats at sea rode the 2004 tsunami quite effectively.

Rolfe.

 

[The_Fire]

I haven't seen anything confirming a fire at any of the nuclear power stations, although there is a large fire at an oil refinery.

Its on a danish newssite, http://nyhederne.tv2.dk/live/tsunami/ , I'll try to hunt down an english site.

 

[Soapy Sam]

The nuclear story seems to have no foundation.

 

[Soapy Sam]

I wonder if the thing to do if you're on an island in the Pacific is to get in a boat and get as far offshore as possible? I seem to recall that boats at sea rode the 2004 tsunami quite effectively.

Rolfe.

Yes, assuming no other weather / sea problems. The danger is overloading of the boat by scared people.

Just watched the staff in a Tokyo supermarket holding bottles on shelves when the tremors started.
Dammit, people, protect yourselves. Never mind the soya!

 

[gumboot]

I wonder if the thing to do if you're on an island in the Pacific is to get in a boat and get as far offshore as possible? I seem to recall that boats at sea rode the 2004 tsunami quite effectively.

Rolfe.

Yup, the safest place to be when a Tsunami is coming is out at sea. As long as you're beyond where the wave will break, you won't notice it at all.

 

[The_Fire]

The nuclear story seems to have no foundation.

Just got a confirmation on live television. Still no source. I'll keep looking. They did talk about it in past time, so its probably been a minor thing.

 

[gumboot]

This?

TOKYO -- A utility company in northeastern Japan has reported a fire in a turbine building of a nuclear power plant after an earthquake shook the region.

Tohoku Electric Power Co. says smoke was observed coming out of the building, which is separate from the plant's reactor, and the cause is under investigation. The plant is in Miyagi prefecture.

Washington Post