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The Largest Recorded Tsunami Was 50 Years Ago
Posted by
kdawson
on Wed Jul 16, 2008 07:07 AM
from the that's-no-wave dept.
from the that's-no-wave dept.
An anonymous reader writes "July marks the 50th anniversary of the world's largest tsunami — a 1,720-foot-tall wave in Lituya Bay, Alaska. It was triggered by a chain reaction of events that began with a magnitude 7.7 earthquake on the Fairweather Fault, which dislodged a rock fall of 40 million cubic yards, that fell 3,000 feet and splashed into the northwest end of Lituya Bay to generate the wave. This article includes survivor accounts, maps, a satellite image, and photos taken right after the event." To be fair, eyewitness accounts put the height of the wave as it came toward their boats at perhaps 100 feet. The tsunami scoured the land of vegetation and soil to a height of 1,720 feet above sea level, however.
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Submission: Largest Recorded Tsunami - 50 Years Ago This Month by Anonymous Coward
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Science: Tsunami Invisibility Cloak 172 comments
BuzzSkyline writes "New Scientist is reporting on a lab-scale experiment that may lead to a tsunami invisibility cloak, which could protect islands, open-ocean platforms and even coastlines from dangerous waves by effectively making them invisible to tsunamis. The technology is based on the same sorts of negative index of refraction ideas that some physicists are exploring as they try to make an optical invisibility cloak, except that it works with water instead of light."
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Feet and yards? (Score:4, Insightful)
Re:Feet and yards? (Score:5, Insightful)
In all seriousness, this happened in the US, so I'd say it's only fitting that the units of measure are ones that Americans use.
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Re: (Score:3, Insightful)
Re:Feet and yards? (Score:5, Interesting)
I used to work in a factory that was owned by a German company, but located in the US. If I would give a drawing labeled in milimeters to our machinists they would balk at it, and I would have to go back and convert it to inches. We had a visiting machinist from Germany and I accidentally gave him a drawing in milimeters to use with our mill which was in inches. Realizing my mistake I offered to correct the drawing. He simply asked what the conversion was. I told him 25.4 mm/in and he came back a little while later with a perfectly machined part.
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Re: (Score:3, Funny)
Re:Feet and yards? (Score:5, Informative)
I blame women. No woman wants to go from weighing 95 units to weighing 209 units.
Great theory, but there are 2.2lbs in a kilo, not 2.2kg in a lb.
So a 95lb woman weighs about 43kg, not 209kg.
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Re: (Score:3, Informative)
It's the new marketing campaign for Viagra.
"Go from 5 inches to 12.7 centimeters over night!"
Re: (Score:3, Funny)
Except that you wouldn't want to multiply a pound by 2.2. You'd want to *divide* a pound by 2.2...
That's an imperial kg, a US kg you multiply. Maybe that's why the US never switched to the metric system.
end sarcasm
Re:Feet and yards? (Score:5, Insightful)
I'm an American and I would so much rather see everything in Metric. I think the main reason this is in the old, crappy system is not because it's written 'for us' or whatever, but because of the year it happened. Though I would think that the guys collecting the data would use metric anyway...
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Re:Feet and yards? (Score:4, Informative)
according to alexa (ok, not the most reliable source) about 60% of the traffic is US.
http://www.alexa.com/data/details/traffic_details/slashdot.org [alexa.com]
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Base ten (Score:5, Insightful)
There is nothing inherently superior about the metric system.
Sure there is. Ease of unit conversion and ease of communication with the REST OF THE FREAKING WORLD. We live in a global economy - we should start acting like it.
Why does dividing by 10 matter so much, anyway? Because you have 10 fingers?
Because we use a base 10 [wikipedia.org] counting system for most calculations. Having a measurement system that is highly compatible with the numeral system most humans use makes sense.
Really, we should be trying to move to a system of measure that is base 2.
Really? Go ahead and tell your mother you came 1011 miles to see her - I'm sure she'll be impressed.
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Re: (Score:3, Funny)
Why does dividing by 10 matter so much, anyway? Because you have 10 fingers?
Because we use a base 10 [wikipedia.org] counting system for most calculations. Having a measurement system that is highly compatible with the numeral system most humans use makes sense.
Really, we should be trying to move to a system of measure that is base 2.
Really? Go ahead and tell your mother you came 1011 miles to see her - I'm sure she'll be impressed.
I'd prefer that we used a hexadecimal system. It is large enough for brevity but also can readily be converted to binary for simplicity. The only advantage a base-10 system has over hexadecimal is that most people have 10_(10) fingers so they know how to count to 10_(10). If they were smart, they'd know how to count to 0x3FF (1023_(10)).
The Mom Test (Score:3, Insightful)
I'd prefer that we used a hexadecimal system.
And how do you propose we convince every non computer geek in the world that this is a good idea? Further are you going to pay for the math classes virtually everyone will need?
Your idea fails the mom test miserably...
Metric bah (Score:5, Funny)
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Re:Metric bah (Score:5, Informative)
1 liter is a volume of 10cm x 10cm x 10cm.
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Our language is base ten (Score:5, Insightful)
"Grandma, I walked eleven miles to see you."
The funny thing about non base-10 number systems is that our language can't say them without spelling them out. The old joke about "There are 10 kinds of people in the world..." isn't very funny if you say it aloud or in your head: "There are two kinds of people in the world" or "There are one zero kinds of people in the world".
So I believe it's our language, not our fingers, that makes base ten feel natural. If we had grown up accustomed to counting "one two three ten eleven twelve thirteen twenty twenty-one twenty-two twenty-three thirty" then base four would feel natural. The characters "2506" would look as strange as hexadecimal and be as impossible to pronounce without spelling or conversion.
By the way, isn't the term "base 10" devoid of meaning? If our system were base four, then "base 10" would mean "base four" since the characters "10" in base four mean "4" in base ten. Whatever base you use, "10" is your way of writing the value of that base.
Back to the tsunami, it's disappointing to hear that the water was 290 fathoms high only very near it's source (the landslide). That's like saying "Your mama's so fat she jumped in the Pacific and made a tsunami a billion nanometers high."
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Re:Our language is base ten (Score:4, Informative)
I believe that we developed a decimal number system because of our fingers. And when the number system developed so did our language. Our adult brains are tuned to decimal numbers because that is the language and system we were educated with. I don't believe that the brains of children are specially tuned to accept a decimal system.
In modern life we don't often use our fingers for manipulating large numbers. In fact our technology works more naturally in binary or hexadecimal. The only thing keeping us using decimal is our language and history, not our fingers.
So the magical thing about SI is not its use of base ten, but rather its use of a consistent base regardless of unit. The cumbersome thing about Imperial units is that the base changes when measuring different things: 12 inches to the foot, 3 feet to the yard, 1760 yards to the mile, 16 ounces to the pound, 4 quarts to the gallon. It's hard to remember which base applies to each unit and it's hard to constantly switch among bases when doing calculations.
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Re:Our language is base ten (Score:4, Insightful)
Shopkeeper: XLIV.
Roman Citizen: Why don't you just SAY XLIV? Who can remember 44?
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Patch the remaining holes (Score:3, Interesting)
I'm not installing a new system until time and angle measurments get upgraded to base 10.
Re: (Score:3, Interesting)
Sure there is. Ease of unit conversion and ease of communication with the REST OF THE FREAKING WORLD. We live in a global economy - we should start acting like it.
Ease of conversion? Are you kidding? It's no easier to convert in either system, unless you only can do math in your head at the moment. Then the metric system has the advantage. If you have some sort of calculator (y'know, most of the time), it's dead easy either way.
Ease of communication doesn't cut it, either. By your logic, we should all be using the same language, and cursing out those heathens who refuse to abandon the language that they're used to. Yet we're not... we accept that people do things in
Re:Base ten (Score:5, Insightful)
we should all be using the same language, and cursing out those heathens who refuse to abandon the language that they're used to. Yet we're not...
Genau meine Rede. Wir sollten einfach alle weiter unsere eigenen Einheiten verwenden und unsere eigene Sprache sprechen. Es macht nämlich zu viel Arbeit, das alles neu zu lernen, nur um mit anderen Menschen kommunizieren zu können und um willkürliche Umrechnungsfaktoren unnötig zu machen. Solche Anstrengungen sind wirklich zu viel verlangt, und bisher hat auch niemand diese Mühen auf sich genommen. Das ist leicht daran erkennbar, in wie vielen verschiedenen Sprachen alleine in diesem Forum Kommentare geschrieben werden. Wer Sarkasmus findet, darf ihn behalten.
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Re:Base ten (Score:4, Insightful)
Ease of conversion? Are you kidding?
Not a bit.
It's no easier to convert in either system...
If you want to believe that dividing by some arbitrary conversion factor is easier than moving a decimal you just go right ahead believing your delusions. By your own arguments it's the same difficulty with a calculator and metric is easier without one. QED metric is easier overall. You should be disappearing in a poof of logic right now.
Ease of communication doesn't cut it, either.
Riiiiiight. [wordpress.com] Because unit conversion mistakes never occur and it's MUCH easier to do unit conversions than to just use the same measurement system everywhere.
Even ignoring social issues There is a measurable economic cost to using multiple measurement systems. It adds unneeded complexity to business, engineering and scientific endeavors especially those that cross international boundaries.
By your logic, we should all be using the same language...
I don't recall ever saying that and I would have said that if that is what I meant. However, English has become the de-facto language of international commerce and scientific discourse if you want to get picky about it. No need to "curse the heathens" since 95% of the world seems to realize that a common measurement system is a useful thing.
Besides imperial units these days are defined against metric units. An inch is explicitly defined as 2.54 centimeters [wikipedia.org]. So you're using metric whether you realize it or not. Why not just cut out the complication and use the real thing?
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Re:Base ten (Score:4, Insightful)
when I don't have a calculator on hand, which is extremely rarely.
What do you sleep with one under your pillow or something? I'm sure you'll be doing lots of unit conversions using a calculator while driving at highway speeds.
I didn't say you said it. I said your logic...
Since you proved you couldn't follow your own logic I'll just keep presuming you can't follow mine. I'm well aware of what follows from the logic of my statements. And for the record, yes having a single language would be very helpful in a lot of ways - and tragic in others. But that is an irrelevant strawman since we are talking about numbers and measurements, not language. 95% of the worlds population already uses metric. If there were no advantage in it they would not have done it.
I somehow doubt you'll find many French people speaking primarily English in their normal lives.
You've never been to France have you? Plenty of folks in France speak English quite fluently and since 89% of schoolchildren [wikipedia.org] in the EU learn English as a second language it's not hard for them to find folks to practice on.
There isn't any significant complication, that's what you're missing.
I'm not missing a thing. There only isn't a complication if you never leave or communicate with no one outside the US. Travel abroad someday and see if anyone shares your naive opinions.
There would be real complication if you try to cram the metric system down people's throats, as you try to force an entire nation of people to use units different from the ones they naturally think in.
So explain to me how 5.7 billion people outside the US managed to utilize metric daily and the 300 million here find it too difficult? Nobody is forcing the US to change and no one could anyway. But that doesn't mean that switching to metric isn't a good idea. Heck it's already been tried once - albeit in . [wikipedia.org]
The advantages afforded by metric are extremely small, and the disadvantages in a conversion would be huge. Why, exactly, would any sane person want to convert?
You have that exactly backwards. The initial conversion costs while significant are trivial compared to the long term savings.
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Re:Feet and yards? (Score:5, Insightful)
"There is nothing inherently superior about the metric system."
Of course there is. It uses powers of ten, which is easy math, it's trivial to relate volume-mass-distance measures (1cm^3=1mL water=1g, 1m^3 of water = 1000kg = 1 tonne), it doesn't have half a dozen wacky variations on the same damn unit (it was 5 ounces: would that be the International avoirdupois ounce, the International troy ounce, the Apothocaries' ounce, the Dutch metric ounce, the Maria Theresa ounce, or, wait, is it possible you mean one of the 3 variations of fluid ounces?). It's the same messy story for "pounds", "gallons", and so on. If you're lucky there are only 2 common versions.
I mean, yes, you're right, it's just a matter of convention and units are always interconvertable, but to say there isn't anything inherently superior about the metric system is nuts. What's convenient about remembering that miles have 5280 feet? Oh, wait, just to be clear I meant an international mile, not the U.S. survey mile (5280 survey feet) or international nautical mile (about 6076 feet). (AAAAAUGH!)
Have you ever noticed that virtually ALL Imperial units are now defined in terms of the metric system? An inch isn't an inch anymore, it's 2.54 centimetres exactly. There's a reason for that -- because the metric system isn't built on a shifting sand of dozens of different archaic national standards and conventions for their usage.
The only thing better about the Imperial system is a metric buttload of inertia in people's brains and the convenience of powers-of-two fractions for some measures. But you can use powers-of-two fractions to express things in metric too if you want.
If you like the Imperial systems please stick with one of them, but you'll never convince me that the metric system is merely on par, especially for anything scientific.
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Re: (Score:3, Funny)
Re:Feet and yards? (Score:5, Informative)
5,280 feet.
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Re: (Score:3, Interesting)
1 and 3/22 miles.
I don't exactly know where we're going with this.
Re: (Score:3, Insightful)
So it's about lowering the bar so anyone can do it without any effort?
I guess this puts some things into perspective.
Re:Feet and yards? (Score:4, Insightful)
Actually the point is that 36430 meters are exactly 36.43 kilometers. The conversion never involves calculations which negatively affect the precision in base ten. If people in the US used a base 2, 12 or 60 number system and a matching unit system, it would make sense, but the imperial unit system is neither advantageous in a different number system nor consistent within itself. It's a relic from an era when measurements didn't have to be exact and estimates were more important than calculations.
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Re: (Score:3, Insightful)
Re: (Score:3, Interesting)
Surely the size of the wave should be measured by the VOLUME of the water displaced, rather than the height.
This one was confined in a bay at its source, so it was very high, but I'll bet the Boxing day 2004 tsunami involved a lot more water, whether you measure it in litres or hogsheads.
Re:Feet and yards? (Score:5, Informative)
from TFA
"The force of the wave removed all trees and vegetation from elevations as high as 1720 feet (524 meters) above sea level. This is the highest wave that has ever been known."
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Canary Islands (Score:3, Informative)
The eye witness account... (Score:4, Insightful)
states they where on 5 fathoms = 30 feet of water, the wave was 100 feet high (I'm guessing the guy means 100 feet above normal level) so that makes the wave 130 feet (40 m.) That is one fudging big wave, but its far from 1725 feet (525m.) high - its far more likely that the 130 feet of wave being pressed up the small valley will have so much force it will keep climbing up to that level.
Re:The eye witness account... (Score:5, Informative)
If you look at the map of the damage, the 1725 figure comes from the slope directly opposite where the honking huge chunk of rock fell 3000' feet to land in the water - which probably displaced all the water straight up and over the spur where the 1725 figure was recorded and then damage along the rest of the bay was more in line with the 100' figure.
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Re:The eye witness account... (Score:4, Insightful)
a 100' wave in 30' of water does not become a 130' wave in 0' of water. This would be equivalent to saying that a 1' wave in 1000' of water becomes a 1001' wave at landfall.
What happens is that as the water becomes more shallow, the leading edge of the wave slows down, while the deeper water at the back of the wave continues to move quickly. As a result, the wave compresses horizontally, and grows vertically.
This is similar to what you're saying about the 130' feet of wave being pushed up the valley -- but it's important to note that the wave "being pushed up the valley" to 1725' is the same thing as saying the wave was 1725' high.
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Similar tsnumai will devastate Eastern Seaboard (Score:4, Informative)
Re: (Score:3, Interesting)
Re: (Score:3, Funny)
Somebody really should be making that movie.
Current day photos? (Score:5, Insightful)
The photos from the following day are impressive, but I'd like to compare it to what it looks like today: How much has been able to regrow in relatively cold climate in 50 years?
Re: (Score:3, Informative)
Well, see for yourself [google.com]. :) :)
Seriously, I've seen a TV program on the 'disaster' and from the ground the you can see where there is an band of young trees around shores of the the bay and older trees further up the slope, but that's about the only visual evidence remaining.
But... (Score:3, Funny)
Where's the satellite picture of the scene before the earthquake?
Questionable height question? (Score:3, Interesting)
OK, when I saw the 1700 ft figure I suspected something was wrong. AFIK, it would take an unbelievable amount of energy to support a mountain of water that high. (Where's frink when I need it?) Even 100 ft indicates a huge amount of energy. It makes total sense if that amount of energy meeting the solidly-planted continental uprising would be re-directed in the direction of least resistance (in this case upslope) until it is dissipated.
The questions that come to mind are things like: How fast was it traveling? Over what area from the epicenter did it travel? What was the actual water level above ground as it rushed upslope? If I ws on the 5th story of a hotel in the water's path, would I have been able to safely watch? Would the hotel have be able to survive the shock if were made out of concrete? (or sticks? or straw?) How much salt was left behind? (The '64 earthquake dropped the level of Cook Inlet by about 40 feet in some places. [That would be 12.192 meters for those of you who are English-unit challenged.] This caused massive salt-water infusion that killed off vegetation for miles inland on parts of the Kenai Peninsula.) How would I model something like that?
It wasn't a tsunami (Score:3, Interesting)
I've been to Lituya Bay. I've walked its shores. I managed to lose a crab pot there. I've talked with one of the survivors. Lituya Bay is a protected harbor used by fishing boats to get out of the weather. I used the harbor to protect myself and a 38' fishing boat from 105 mph winds one summer (1967). There is a very narrow passage to get into the harbor. You have to line up to lights (night) or white sticks (day) and traverse between a large sandspit and the shore. In the middle of the bay is an island. It contains ruins of an old French fur trapping venture. At the back of the bay is a glacier. When the earthquake struck a piece of the glacier broke off and entered the bay, quickly, causing a huge wave. The wave rushed away from the back of the bay, washed over the island, and washed several fishing boats over the sandspit into the Gulf of Alaska, snapping their anchor chains easily.
You can see that this was no ordinary 'tsunami.' The wave did not come from the sea, but from the shore and moved outward. take a look on Google Earth and you will see what I mean. 58*37'52" North, 137*36'03" East.
Re: (Score:3, Funny)
Re:Units (Score:5, Funny)
This is kdawson we're talking about. We should be thankful he gave us any sort of units at all.
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Re: (Score:3, Insightful)
said the guy that wasted the first post spot with 'frosty piss'... class act indeed. Pot, kettle, black.
Re:50 years ago? (Score:5, Funny)
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Re:"To be fair" ot "To be correct"? (Score:5, Insightful)
A tsunami may be only a few feet higher than average sea level as it crosses oceans, but when the mass of water piles up as it reaches shore, the runup can go hundreds of feet above sea level. If you're standing on the slope at a height of 800 feet above sea level, and the tsunami starts, which is more 'real' about the height of the tsunami -- the hundred-foot height of the wave in the open water of the bay, or that the runup is going to scour the ground clean almost a thousand feet farther up the slope than where you're standing?
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Re:We all know what really caused this... (Score:4, Informative)
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