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'Merging Tsunami' Amplified Destruction In Japan

Soulskill posted more than 2 years ago | from the destructive-interference dept.

Earth 50

Hugh Pickens writes "The magnitude-9.0 Tohoku-Oki temblor, the fifth-most powerful quake ever recorded, triggered a tsunami that doubled in intensity over rugged ocean ridges, amplifying its destructive power at landfall, as seen in data from NASA and European radar satellites that captured at least two wave fronts that day, which merged to form a single, double-high wave far out at sea. This wave was capable of traveling long distances without losing power. Ocean ridges and undersea mountain chains pushed the waves together along certain directions from the tsunami's origin. 'It was a one-in-10-million chance that we were able to observe this double wave with satellites,' says study team member Y. Tony Song. 'Researchers have suspected for decades that such 'merging tsunamis' might have been responsible for the 1960 Chilean tsunami that killed about 200 people in Japan and Hawaii, but nobody had definitively observed a merging tsunami until now.' The study suggests scientists may be able to create maps that take into account all undersea topography, even sub-sea ridges and mountains far from shore to help scientists improve tsunami forecasts."

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50 comments

Nature has it out for us! (2, Funny)

Anonymous Coward | more than 2 years ago | (#38289246)

I say we teach that bitch a lesson she'll understand!

Re:Nature has it out for us! (2)

FBeans (2201802) | more than 2 years ago | (#38289258)

So we can watch and forecast them. But all we can really do in the end is... Rrrrrrrrrrruuuuuuuuuuuunnnnnnnnn!!!!!!!!!

Re:Nature has it out for us! (4, Funny)

indeterminator (1829904) | more than 2 years ago | (#38289456)

I though there was some commission to prevent mergers that cause harm to the general public?

Re:Nature has it out for us! (0)

Anonymous Coward | more than 2 years ago | (#38289886)

As always (oceanic) bodies do not really care for regulatory comissions and do whatever they want below the surface.

Re:Nature has it out for us! (1)

Rashdot (845549) | more than 2 years ago | (#38289514)

There's a hilarious "World Nature Bashing Foundation" site in Dutch at www.wnbf.nl to take care of that, by a Dutch amateur stand up comedian.

Quotes from his show about "Nature has it out for us":

Showing picture of an old abandoned bike: "I parked my bike with inflated tires three years ago and sure enough, nature flattened them."

A picture of a very old tiled path: "You build a nice, straight path, and nature will destroy it in a few years time. But it doesn't work the other way around: throw a bunch of tiles in your yard, come back a few years later and there won't be a nice straight path."

Re:Nature has it out for us! (0)

hcs_$reboot (1536101) | more than 2 years ago | (#38289724)

I say we teach that bitch a lesson she'll understand!

Global warming, pollution, nuclear waste etc... She's getting a message she is not going to forget for a while...

Re:Nature has it out for us! (1)

v1 (525388) | more than 2 years ago | (#38290158)

Global warming, pollution, nuclear waste etc... She's getting a message she is not going to forget for a while...

So who's to say she's not the one giving the paybacks as of lately?

I'll just post this (-1)

Anonymous Coward | more than 2 years ago | (#38289278)

Because I cant think of anything else that will get modded a lot

Thinking through the uses... (4, Interesting)

RogueyWon (735973) | more than 2 years ago | (#38289326)

Better understanding and forecasting would be a fantastic thing. It would certainly save lives. However, after watching the footage of the tsunami in question, there's a little part of my brain that wonders whether it would do much more than tweak the odds for people in a few marginal cases.

I suppose where there's a much clearer use for this is in making infrastructure and resilience planning decisions. It will never be practical to say "people shouldn't live in areas that might be hit by tsunamis". As the "Boxing Day" tsunami demonstrated, the areas in question are absolutely vast - and as the Japanese tsunami demonstrated, they can stretch miles inland. I just don't see how countries could afford to give up such huge tracts of habitable land to mitigate against the risk of "once every couple of centuries" events. What might be practical, however, is to think about how to site critical pieces of infrastructure (such as... say... nuclear power plants, as well as hospitals, emergency response centres, transportation hubs) so as to minimise their exposure to these events - and understanding the paths that future tsunamis are likely to follow is going to be key to that.

And protecting your key infrastructure is vital to saving lives in the days and weeks after a catastrophe - particularly in nations less wealthy and less resilient than Japan (which understandably struggled even despite those advantages).

Re:Thinking through the uses... (2)

fsckmnky (2505008) | more than 2 years ago | (#38289366)

I'm no expert on earthquakes and tsunamis, but, if they have a general idea of locations of faults, or probabilities where earthquakes are highly likely to occur, the mathematics behind determining tsunami combinations might help them better evaluate the risk for any given location. If the old method of thinking or planning was to prepare for a single event, this could help them determine the probability of a merged wave.

Barely educated speculation on my part.

Re:Thinking through the uses... (5, Interesting)

CheeseyDJ (800272) | more than 2 years ago | (#38289440)

What might be practical, however, is to think about how to site critical pieces of infrastructure (such as... say... nuclear power plants...

Honest question - does anyone know why the Fukushima plant was built on the east coast of Japan, facing the bomb-waiting-to-go-off [google.co.uk] that is the massive subduction zone a few miles off shore?

Why wasn't it built on the west coast, so it was sheltered by the island itself? I know hindsight is a wonderful thing, but looking at the map this seems like a schoolboy error to me.

Re:Thinking through the uses... (4, Interesting)

RogueyWon (735973) | more than 2 years ago | (#38289470)

My vague memory from articles at the time is that the Fukushima plant was built before knowledge of tsunamis is as advanced as it is today, and that it had a degree of resilience built in against a "more normal" tsunami, rather than the absolute monster that did appear.

Of course, it's worth remembering that while a lot of people had their lives disrupted, the casualties directly caused by Fukushima were limited. If you're looking for examples of disastrous infrastructure planning decisions with fatal consequences, I'd suggest reading up on the Vajont Dam [wikipedia.org] . I've seen this used in public sector training courses as a cautionary example of what the consequences of rushed, sloppy or biased planning decisions can be. It also, largely through coincidence, involves a tsunami (and one with a much, much greater wave height than that which hit Japan this year) - and a freshwater one to boot.

Re:Thinking through the uses... (3, Insightful)

necro81 (917438) | more than 2 years ago | (#38289892)

the Fukushima plant was built before knowledge of tsunamis is as advanced as it is today, and that it had a degree of resilience built in against a "more normal" tsunami, rather than the absolute monster that did appear

Here is a counterpoint [slashdot.org] . Risk management is not a one-time thing: if you are in a risky business (be is security, medical safety, nuclear power, etc.), you need to continually re-assess what risks exist and whether you have properly mitigated them. Failure to take new knowledge, such as improved tsunami science, into account as it becomes available and act on it appropriately is simply negligent.

Re:Thinking through the uses... (1)

khallow (566160) | more than 2 years ago | (#38295028)

So where's the evidence that tsunami science had become "available"? And it's worth noting that the link is to an article that says the Tokai plant survived intact only because it was hit by a much smaller tsunami than the Fukushima plant. There's no lesson about risk management there.

Re:Thinking through the uses... (2)

TheTurtlesMoves (1442727) | more than 2 years ago | (#38289552)

the whole idea of plate tectonics was only just starting to gain traction in scientific circles at the time. Basically they didn't know and in fact they realistically couldn't know.

Re:Thinking through the uses... (0)

Anonymous Coward | more than 2 years ago | (#38289574)

Scientific consensus vilified all those static continent deniers. It took decades for actual science, not consensus science, to win out.

Re:Thinking through the uses... (1)

antifoidulus (807088) | more than 2 years ago | (#38289584)

I would be willing to be geography has a lot to do with it. Most of the central part of Honshu(the main island) is incredibly mountainous. In order to run power from the west coast to Tokyo and the surrounding prefectures, you would have to run a lot of power lines through those mountains. This would be incredibly difficult as well as incredibly expensive, so my guess is that they try to keep the power generation on the same side of the island as the electricity is used on.

Re:Thinking through the uses... (2)

Luckyo (1726890) | more than 2 years ago | (#38289676)

Electric grid of Japan is most likely at fault. It's not unified like in most Western countries, and is instead split between power generating companies. Ability to transfer electricity between different grids is nonexistent.

There is a geographical reason for this: Japan is a very mountainous area, and pulling and maintaining electric cables across mountains is astronomically expensive.

Re:Thinking through the uses... (3, Informative)

JanneM (7445) | more than 2 years ago | (#38290552)

it is split in two parts only; eastern and western Japan, and the split is because the power frequency differs, with 50Hz in the east (including Tokyo and northern Japan) and 60Hz in the west with Osaka, and Kyuushuu and so on. The grids are pretty dense otherwise, but there's only three points capable of converting power between the two grids.

And the reason has nothing to with being mountainous. Simply, as electricity was first introduced, different companies in Tokyo and Osaka bought their power generation stuff from different places, with the Tokyo company buying from Germany (which used 50Hz) and the Osaka one from the US (which used 60Hz). With no regulation in place for the burgeoning industry and no short-term reason for the companies to agree over such things, the country split, electrically, and the split remains today.

Re:Thinking through the uses... (1)

JanneM (7445) | more than 2 years ago | (#38290582)

There's plenty of power plants along the Japan sea as well. I strongly suspect the placement is dictated more by the availability of a good site and local political willingness to accept a nuclear power plant within the prefecture.

Re:Thinking through the uses... (1)

tlhIngan (30335) | more than 2 years ago | (#38292928)

There's plenty of power plants along the Japan sea as well. I strongly suspect the placement is dictated more by the availability of a good site and local political willingness to accept a nuclear power plant within the prefecture.

And the availability of water. Lots and lots of water.

Those towers we think of for nuclear power plants are cooling towers because fission produces a LOT of heat. So much that air cooling isn't enough. So nuclear plants have to be beside a body of water large enough to handle the heat output from the reaction.

This basically limits the placement of a nuclear plant to either on the coast or near a large inland body of water. Unfortunately, Japan doesn't have inland bodies of water, or large ones at that, so the only places to build are... along the coast.

Re:Thinking through the uses... (0)

Anonymous Coward | more than 2 years ago | (#38290698)

Because noone lives there (having experienced numerous tsunami, even in living memory), so noone can complain it is in their backyard.

Re:Thinking through the uses... (1)

bluemonq (812827) | more than 2 years ago | (#38293592)

Chalk it up to an unfortunate faulty understanding of the geology of the area. Before the quake, it was expected that the largest quake -- and therefore tsunamis that resulted from that quake -- that could come out of that area was right around an 8. So the reactor was designed to survive an 8.5, and the seawall in that region was designed to block an 8-ish tsunami.

Unfortunately, they were wrong.

Re:Thinking through the uses... (1)

khallow (566160) | more than 2 years ago | (#38294966)

Honest question - does anyone know why the Fukushima plant was built on the east coast of Japan, facing the bomb-waiting-to-go-off that is the massive subduction zone a few miles off shore?

Because that is where the water is. Nuclear plants are fundamentally, a heat engine with heat flowing from a hot sink, the reactor core to a cold sink, here the Pacific Ocean.

Re:Thinking through the uses... (0)

Anonymous Coward | more than 2 years ago | (#38304354)

So there's no water on the west side of the island?

Re:Thinking through the uses... (1)

khallow (566160) | more than 2 years ago | (#38304902)

There's already nuclear plants on the west side. And there's probably tsunami risks on that side of the island too.

Re:Thinking through the uses... (1)

mapkinase (958129) | more than 2 years ago | (#38289652)

The catastrophes are reminders for us, humans, about fragility of human life.

If you are a man of religion, like me, you think of God sending us those reminders.

If you are a man of science, like me, you think of limits of human power.

In both scenarios, it is humbling.

Re:Thinking through the uses... (1)

AmiMoJo (196126) | more than 2 years ago | (#38289742)

However, after watching the footage of the tsunami in question, there's a little part of my brain that wonders whether it would do much more than tweak the odds for people in a few marginal cases.

There are actually quite a few things you can do to prevent tsunami causing that much damage. For example building under-sea groins near the shore that take much of the energy of the wave out of it, reducing its height and speed.

Japan has an extensive network of under-sea sensors to provide early warning of earthquakes and tsunami. Sometimes a warning flashes up on the TV before you feel the tremors (they time time to radiate out from the epicentre), and then a few seconds later they announce if there will be a tsunami too. Japan gets magnitude 5 quakes all the time and the waves are typically around 50cm. I'm not entirely sure why the very large March tsunami was not detected by the existing system, but I believe it is to do with the wave height being inferred from the size and location of the quake which in that instance was pretty much off the chart.

Re:Thinking through the uses... (1)

khallow (566160) | more than 2 years ago | (#38294936)

However, after watching the footage of the tsunami in question, there's a little part of my brain that wonders whether it would do much more than tweak the odds for people in a few marginal cases

They would have had up to an hour of warning. Now, if you're trapped under rubble, then you're out of luck. But even for people on foot, that gives them a pretty good chance.

Error in summary. (1)

EmagGeek (574360) | more than 2 years ago | (#38289380)

"This wave was capable of traveling long distances without losing power."

No, it wasn't.

Re:Error in summary. (0)

Anonymous Coward | more than 2 years ago | (#38289464)

You're being excessively literal.

Re:Error in summary. (1)

EmagGeek (574360) | more than 2 years ago | (#38289708)

The summary writer was being excessively lazy at the expense of accuracy. That is not acceptable.

Re:Error in summary. (1)

mcgrew (92797) | more than 2 years ago | (#38292426)

The summary writer was being excessively lazy at the expense of accuracy. That is not acceptable.

Well, what are you going to do? Lower his pay?

Re:Error in summary. (0)

Anonymous Coward | more than 2 years ago | (#38289752)

You're being excessively literal.

You must be new here. This is the Land of Slashdot, where pedants are crouching at every corner, ready to pounce on any unsuspecting neophyte who dares to rear up his head and speak up without taking into account all the possible interpretations that can conceivably apply to every single word they utter.

Now seriously, I think the GP was just trying to be a jerk. That quote from TFS was self-explanatory.

Re:Error in summary. (1)

Bill Currie (487) | more than 2 years ago | (#38289612)

Sure, it was capable of traveling long distances without losing power, and it would have too, if a rather large island hadn't been in the way.

Re:Error in summary. (1)

Muad'Dave (255648) | more than 2 years ago | (#38289730)

Very nearly literally so in the case of a soliton [wikipedia.org] .

Re:Error in summary. (1)

Baloroth (2370816) | more than 2 years ago | (#38290162)

A soliton was my first thought on reading the summary. Such waves are possible in the ocean (they have been observed in canals before.) No mention in TFA that that was the case here though

Nature does Mapreduce (0)

Anonymous Coward | more than 2 years ago | (#38289776)

with waves. Nature has googled man from the very beginning.

Animated version from NOAA (2)

rwa2 (4391) | more than 2 years ago | (#38289890)

I know you really want to see the animated version, with narration:
http://youtu.be/Lo5uH1UJF4A [youtu.be]

Somewhere there's another awesome animation of a huge tsunami caused by an earthquake off the coast of Chile. The waves travel across the Pacific and swing around Hawaii, which acts like a lens and focuses multiple waves that converge right on Japan. Fun times!

conservation of energy (4, Insightful)

v1 (525388) | more than 2 years ago | (#38290230)

What I find most interesting about tsunami is their ability to move energy so efficiently, with next to no loss. It's a wave traveling in a medium that has very little internal friction. This allows it to travel a tremendous distance without losing a lot of its energy.

The other thing is how it moves the energy when it's out in the ocean. Think of the tsunami when it's out in the middle of the ocean, and is generating a swell of say an inch. It's lifting a two mile column of water an inch up. That's a huge amount of energy.

When that wave approaches land, the distance from sea floor to sea level is much smaller, but the energy is mostly still there. So instead of raising it an inch, you get several meters. They refer to this as "coastal amplification" or something like that, but it's quite the nasty thing to pull when it hits landfall. If you were in a little skiff a few miles off the coast you may not even notice your boat rock, but if you were in that same boat a few hundred feet from the beach you'd be surfing in on a 25 meter high wave. What an amazing difference! It's no wonder Japan got yachts parked on streets a mile in from the coast.

Ocean floor topography plays a role in this too. And then you get effects like waves reflecting off entire continents and other large land masses, and opposite cases where little pockets here and there are sheltered from the effects due random luck involving coastal features. Tsunami are easily just as interesting a study as tornadoes or typhoons in their subtlety and power.

Should have used Git. (1)

VortexCortex (1117377) | more than 2 years ago | (#38290040)

'Merging Tsunami' Amplified Destruction In Japan

The last time I merged two SVN branches it more than just amplified the clusterfsck -- The process itself caused caused quite a bit of its own.

Prevention of Tsunamis (0)

Anonymous Coward | more than 2 years ago | (#38291698)

Perhaps in the future we can use a bomb or other device to deflect the energy and prevent the tsunami from maintaining its momentum long enough to reach this kind of magnitude.

200 in Japan and Hawaii? (0)

Anonymous Coward | more than 2 years ago | (#38302988)

From the summary...

> the 1960 Chilean tsunami that killed about 200 people in Japan and Hawaii,

May want to mention the 2,500-6,000 victims in Chile too.... Just saying.

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