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Old 02-29-2012, 05:56 PM   #796
Sky Captain
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Quickly evacuating entire Tokyo region would be impossible. It is not so much about how to transport and where to put all those people, but how to support them. Water, food, shelter, sanitation, medicine. Quickly providing all that in some Australian desert would be impossible. Such evacuation attempt probably would kill more through accidents and disase than all four Fukushima reactors spontaneusly exploding Chernobyl style.
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Old 02-29-2012, 06:18 PM   #797
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Transport and logistics issues aside, I wonder how "hugely overcrowded" China actually is. Especially in regard to a few million people.

Rising sea levels are far less immediate a threat than nuclear contamination (or lack of infrastructure). It isn't like islands are magically getting swallowed up by the sea.

If for whatever reason the best cause of action were to evacuate a large portion of Japan, you'd have severe trouble doing so. It is the tenth most populous country on Earth, after all.
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Old 02-29-2012, 06:39 PM   #798
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The two airports of Tokyo alone manage 100 million passengers per year at civilian operations. If you would reduce things to the pure uncomfortable hauling of people from A to B without transporting anything but fuel from B to A, you should manage about 300 million passengers in the same time, alone by higher flight rates possible if you do the turn around elsewhere. Let the little baggage of the people be transported by ship or train, and you get another increase in capacity, maybe up to 400% in total. This would mean you could evacuate Tokyo in less than two weeks by aircraft alone.

Two weeks is a pretty good value for the kind of danger, we don't speak of Godzilla approaching.
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Old 02-29-2012, 07:24 PM   #799
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Quote:
Originally Posted by T.Neo View Post
 Rising sea levels are far less immediate a threat than nuclear contamination (or lack of infrastructure). It isn't like islands are magically getting swallowed up by the sea.
Bit off topic, but they are.

Not due to seal level rise, but because tectonic plates drift and often take islands under water. You'll often find reports in the media about global warming and seal level rise. They'll go out to an island and show peer and structures 10 meters under water. What they're failing to consider is that seal level rise due to increased water temperature - you know, water expands - is currently at about 20 to 30 cm.
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Old 02-29-2012, 08:06 PM   #800
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Originally Posted by Urwumpe View Post
 
Two weeks is a pretty good value for the kind of danger, we don't speak of Godzilla approaching.
Wouldn't it be more effective to tell people to seal their doors and windows as good as possible and wait few days till radiation levels decrease in a hypothetical scenario where Fukushima exploded like Chernobyl and spewed fallout over Tokyo? Most radioactive stuff with short half lifes decay quickly leaving isotopes with longer half lifes but those emit less radiation. When fallout is over launch massive decontamination operation and evacuate only those areas that are too radioactive for safe long term habitation and can't be effectively decontaminated.
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Old 02-29-2012, 08:22 PM   #801
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 Wouldn't it be more effective to tell people to seal their doors and windows as good as possible and wait few days till radiation levels decrease in a hypothetical scenario where Fukushima exploded like Chernobyl and spewed fallout over Tokyo? Most radioactive stuff with short half lifes decay quickly leaving isotopes with longer half lifes but those emit less radiation. When fallout is over launch massive decontamination operation and evacuate only those areas that are too radioactive for safe long term habitation and can't be effectively decontaminated.
Well, depends on the kind of radiation and its vector. Houses are no NBC shelters. You can't seal them off. And you can't stay in your house for weeks. You need to leave it pretty often in that time. such protection is good enough, if you have toxic fumes because of a fire, that will disperse after a few hours and which you can seal off for a short time.

Most fission products in a reactor are pretty annoying for weeks, especially in dust form. The typical reactor poison of xenon-135 for example, decays in about 3 days (9 hours half-life), and is gaseous. You can't seal it off that easily, and beta decay can penetrate the simple protections. Plutonium is harmful even in traces.

Next, you need to remember that not everything is really harmless after it decayed. The decay chains of most stuff there mean something can even change from gas to dust and back during the time it is harmful.

Iodine and Calcium, the worst substances in that context for the human body, because your body absorbs them in huge quantities, are harmful for years, if a reactor would suffer from an explosion to spread them over the needed distance. The hot temperatures of the Chernobyl fire had been a blessing, since it spread the materials over a huge region, so we only had a few small hot spots where the material was concentrated. Without such a fire, the material would not travel that far and would concentrate locally, in the worst case mostly around the reactor and Tokyo, if the weather conditions are like that. Which was not that unlikely last year, in case of the weather. We had exceptional weather with late rain that time.
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Old 02-29-2012, 11:30 PM   #802
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Bit off topic, but they are.
Can you give an example of an island that became submerged over short (i.e. sub-century) timescales due to tectonic activity?
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Old 03-01-2012, 01:14 AM   #803
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Originally Posted by T.Neo View Post
 Can you give an example of an island that became submerged over short (i.e. sub-century) timescales due to tectonic activity?
Of course not. It's not like I go around memorizing names of sunken islands. I wouldn't be surprised if they exists. The sink rate can be as high as several 10 cm per years in some places.
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Old 03-10-2013, 01:13 PM   #804
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Default Japan quake 'heard at edge of space'

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The great Tohoku earthquake in Japan two years ago was so big its effects were even felt at the edge of space.

Scientists say the Magnitude 9.0 tremor on 11 March 2011 sent a ripple of sound through the atmosphere that was picked up by the Goce satellite.

Its super-sensitive instrumentation was able to detect the disturbance as it passed through the thin wisps of air still present 255km above the Earth.

The observation is reported in the journal Geophysical Research Letters.

It has long been recognised that major quakes will generate very low-frequency acoustic waves, or infrasound - a type of deep rumble at frequencies below those discernible to the human ear. But no spacecraft in orbit has had the capability to record them, until now.

"We've looked for this signal before with other satellites and haven't seen it, and I think that's because you need an incredibly fine instrument," said Dr Rune Floberghagen from the European Space Agency (Esa).
Continue reading the main story

"Goce's accelerometers are about a hundred times more sensitive than any previous instrumentation and we detected the acoustic wave not once, but twice - passing through it over the Pacific and over Europe," the mission manager told BBC News.

Goce's prime purpose is to map very subtle differences in the pull of gravity across the surface of the Earth caused by the uneven distribution of mass within the planet.

These variations produce almost imperceptible changes in the velocity of the satellite as it flies overhead and which it records with those high-precision accelerometers.

This gravity signal is very weak, however, and that means Goce must fly incredibly low to sense it - so low, in fact, that it actually drags through the top of the atmosphere.
Tsunami Monday marks the second anniversary of the quake and tsunami that claimed more than 15,000 lives

It is these special circumstances that put the satellite in a position to detect the infrasonic disturbance on 11 March 2011.

The acoustic waves perturbed the density of air molecules and changed their speed. It was the faintest of winds at an altitude of 255km, but strong enough to be registered by Goce.

The Esa spacecraft encountered the signal as it passed over the Pacific some 30 minutes after the onset of the M9.0 event, and then again 25 minutes later as it moved across Europe.

Because of the way the accelerometers are arranged in Goce, it was possible to reconstruct the detection in three dimensions and so confidently trace the infrasound back to its source - the earthquake.
Goce geoid (Esa) Goce's principal objective is to make maps of the variation in the pull of gravity across the Earth

"If you have a small ripple in density, it would be hard to conclude beyond any reasonable doubt that this was due to the earthquake," explained Dr Floberghagen. "But the fact that we have a very significant density perturbation, with the shape predicted by all the acoustic models, and the fact that we picked it up again on the other side of the Earth where you would expect to find it - that's perfect."

Scientists can already study earthquakes from space, in particular through the use of radar to map the deformation of the ground that results when faults rupture. But it remains to be seen how useful an acoustic sensor placed in a low-Earth orbit might be.

Tohoku was an exceptional event and this may explain why Goce, on this occasion, was able to pick it up.

Buoyed by their success, however, scientists on the mission are checking through the satellite's data to see if an infrasonic signal was also recorded when an asteroid entered the atmosphere over the Russian city of Chelyabinsk last month. The entry's infrasound signature was certainly evident to listening stations on the ground.
Meteor The Chelyabinsk meteor is known to have produced a big infrasound signal - but is it in Goce's data?

"Ever since we've flown this type of instrument - accelerometers - in space, people have been looking for the acoustic beat from earthquakes, because that could be used to understand the way tremors propagate not only through the Earth but through the Earth environment.

"We'll see; time will tell. But just the idea of an acoustic sensor in space is pretty cool," Dr Floberghagen told BBC News.

Goce itself is running low on fuel and is nearing the end of its mission.

Esa will lower its orbit in June to below 230km to try to obtain even finer detail on Earth's gravity field. The agency is then expected to command the satellite to come out of the sky and fall back to Earth in November.
Source: http://www.bbc.co.uk/news/science-environment-21730887
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Old 10-25-2013, 06:14 PM   #805
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Default Fukushima tsunami alert after earthquake

Another Earthquake has just hit off the coast of Fukushima.

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Japan has issued a tsunami advisory for the Fukushima area - where the crippled nuclear plant is located - after a powerful quake in the Pacific Ocean.


The Japan Meteorological Agency said a small tsunami - up to one metre (3.3ft) - could reach the eastern coast, but no damage was expected.
It said the 6.8 magnitude quake struck at a depth of 10km (six miles), about 320km off Japan's eastern coast.


The US Geological Survey said it was a 7.3 magnitude earthquake.
Source: http://www.bbc.co.uk/news/world-asia-24677578
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