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Researchers Plot Course Of Ancient American Tsunami (902AD)
Ananova ^ | 10-28-2002

Posted on 10/28/2002 4:27:53 PM PST by blam

Researchers plot course of ancient American tsunami

Researchers have calculated the scale of a giant wave that devastated the north west coast of America 1,100 years ago.

Japanese scientists used computer modelling to recreate the devastation from the ancient tsunami.

The team from the Disaster Reduction and Human Renovation Institution in Kobe say the work will help planners minimise the impact of any future wave.

The researchers took clues from silt deposits found in the Puget Sound, a Pacific inlet above earthquake fault lines in the Seattle area.

Experts say the tsunami could have reached up to seven metres in height and penetrated 300 metres inland.

They say it's possible a tsunami of similar scale could hit the Puget Sound in the event of a future quake.

Nature says that the research will be incorporated into maps predicting the areas most at risk.

Story filed: 11:06 Monday 28th October 2002


TOPICS: News/Current Events
KEYWORDS: 902ad; alaska; american; archaeology; atlantis; california; cascadia; catastrophism; earthquake; ggg; godsgravesglyphs; hawaii; history; newyork; newyorkcity; oregon; pacific; plot; pugetsound; researchers; seattle; tsunami; washington
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It just goes to show you, It's always something!
1 posted on 10/28/2002 4:27:53 PM PST by blam
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To: LostTribe; RightWhale
Heads up in your neighborhood.
2 posted on 10/28/2002 4:41:56 PM PST by blam
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To: blam
Seems like there is evidence of that "big one" at various points along the Pacific Coast. I had heard of it before, but can't recall any specifics.
3 posted on 10/28/2002 4:44:26 PM PST by LostTribe
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To: blam
This gave me the chills....if it happened once,it can happen again. I am glad that I live in Ohio.
4 posted on 10/28/2002 4:48:35 PM PST by ruoflaw
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To: LostTribe
"Seems like there is evidence of that "big one" at various points along the Pacific Coast. I had heard of it before, but can't recall any specifics."

Ditto. This is the first time I recall seeing a date.

5 posted on 10/28/2002 4:58:53 PM PST by blam
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To: blam
Check out stories on the inevitable La Palma tsunami
6 posted on 10/28/2002 4:59:36 PM PST by martin_fierro
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To: blam
We're 300 miles inland, but only 400 feet above sea level. If the next tsunami reaches Fairbanks, it would be an epochial event.
7 posted on 10/28/2002 5:00:43 PM PST by RightWhale
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To: blam
Dude, Surf's up!
8 posted on 10/28/2002 5:03:52 PM PST by commish
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To: blam
How is a 23 foot wave the "Big One"?
9 posted on 10/28/2002 5:16:35 PM PST by Mr. Lucky
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To: RightWhale
Experts say the tsunami could have reached up to seven metres in height and penetrated 300 metres inland.

eh--is there a problem with scale here, like maybe a misplaced decimal? because a 25 ft wave penetrating 1000 ft inland doesn't sound like much to me.

10 posted on 10/28/2002 5:20:05 PM PST by gusopol3
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To: Mr. Lucky
How is a 23 foot wave the "Big One"?

If it is 23 feet out in the deep ocean and covers a large area, it represents a huge mass of water. By the time it reaches shore and piles up on itself it can be hundreds of feet high and crash far inland.

11 posted on 10/28/2002 5:21:56 PM PST by RightWhale
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To: gusopol3
I've surfed bigger waves in Santa Cruz
12 posted on 10/28/2002 5:23:07 PM PST by clamper1797
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To: gusopol3
A tsunami in deep water may be nearly unnoticeable if you are in a ship, maybe only 3 feet high. In shallow water it becomes a huge wave.
13 posted on 10/28/2002 5:24:14 PM PST by RightWhale
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To: RightWhale
I would believe 700 feet high and 300 miles inland
14 posted on 10/28/2002 5:25:09 PM PST by clamper1797
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To: ruoflaw
I am glad that I live in Ohio.

Near New Madrid, the epicenter of the biggest 'quake in the contiguous United States...

15 posted on 10/28/2002 5:25:45 PM PST by null and void
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To: martin_fierro
"Why the only certainty about the La Palma tsunami is that it WILL happen

Insurance Day
Scott Farley
October 18 2000

IT looked like a scene from Hollywood‘s latest summer blockbuster. But the image of a giant tsunami engulfing Manhattan island published in last week‘s Insurance Day did not come from the over-active imagination of an eager scriptwriter.

It was, in fact, an artist‘s impression of a very real threat. One that has been established through years of authoritative research from scientists at the Benfield Greig Hazard Research Centre at University College, London.

Their work has established that much of La Palma, the most volcanically active of the Canary Islands, is now inherently unstable.

Another eruption could cause half the island to simply fall away and crash into the ocean. The resulting impact would generate a giant wave big enough to sweep westwards across the Atlantic and devastate the entire eastern seaboard of the United States.

Such theories of enormous tsunamis being generated by island landslides first emerged from studies of the seabed around Hawaii in the Pacific. Here great slabs of rock were identified which, it was suggested, had slipped below the surface after detaching themselves from the main islands as a result of volcanic activity.

Meanwhile, in the Canaries Dr Simon Day, of the Benfield Greig Centre, began mapping La Palma in 1994.

His studies of the summit area gradually uncovered dozens of volcanic vents formed over a period of hundreds of thousands of years by various volcanic eruptions.

All the evidence pointed to one startling conclusion - that the western half of the volcano is gradually separating itself from the eastern half.

Another important realisation was the influence of water within the rock. When this is heated by magma rising to the surface it expands and adds to the pressure on the island to fragment.

This particular effect may well prove significantly more crucial in years to come, speculates Dr Day. He believes the process of global warming could contribute to the heating of water and make the set of conditions necessary for a landslide more likely.

“There is an interesting possibility that the collapse may become much more likely over the next century or so because of global warming,” he warned.

So what happens when the fracture does take place? Well, quite simply, 500bn tonnes of rock plunge straight into the ocean.

In an attempt to determine the nature and impact of such an event Dr Day co-operated with researchers from the Swiss Federal Institute of Technology in Zurich.

Here a laboratory model was constructed of La Palma island in a wave tank. The collapse was then reconstructed and recorded by a high-speed camera.

The results were incredible. They showed that as the rock crashed into the ocean it would in real life generate a wave up to 650 m tall.

“The models still have a lot of uncertainty attached to them, but the wave height is estimated at around 650 m and that is in my view using a number of conservative assumptions,” explained Dr Day.

“Other methods have predicted anything from 1 km to 3 km.

“As the wave spreads out it looses its strength, but it will still be several tens of metres high as it strikes the United States.”

But it would not be just the eastern seaboard of America to suffer. The wave would spread out in a circular pattern like the ripples generated by dropping a stone into a pond.

They would reach as far as Florida and the Caribbean as well as bending back to hit Western Europe.

The big question of course is how probable is this nightmare scenario? It is one which is answered simply by Professor Bill McGuire, also from the Benfield Greig Centre.

“There‘s no if about it,” he stated. “It will happen, it‘s just a question of when.”

But when exactly? Here at least there is some comfort. While the landslide will be caused by volcanic activity it will not necessarily happen the very next time the island erupts.

Indeed, it may take many more eruptions before the split finally occurs.

And eruptions do not happen on a regular basis.

The last one was in 1971 and those in the future may only strike at intervals of anything from a few decades to a couple of centuries.

The probability of a giant tsunami being generated in any one century, therefore, is estimated by Dr Day at 5%.

When it does finally happen, however, there may be little opportunity for New York and the rest of the eastern coast of the United States to head for the hills.

“No volcano ever erupts without some warning,” said Professor McGuire.

“The difficult thing is determining whether that particular eruption will be the one to cause the landslide or not.

“When it does go it will go in a matter of minutes and I wouldn‘t like to be around measuring things at that point.”New York (right) and much else could be devastated by a tsunami emanating from the eruption of La Palma, the most volcanic of the Canary islands, whose main port is Las Palmas (below). A volcanic eruption (left) last came on La Palma in 1971 - and those in future may come at any time “The difficult thing is determining whether that particular eruption will be the one to cause the landslide or not.

16 posted on 10/28/2002 5:26:33 PM PST by blam
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To: RightWhale
This is why I've invested in some future beachfront property in the Texas Hill Country!
17 posted on 10/28/2002 5:36:59 PM PST by sam_paine
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To: clamper1797
To reach 300 miles inland it would have to be much more than 700 feet high as it contacts the shore. A very rough estimate: Maybe 10 to 20 miles high, clearly impossible since there isn't enough deep water in the ocean. The 700 foot crest might reach 3 miles inland, probably less in most places.
18 posted on 10/28/2002 5:40:38 PM PST by RightWhale
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To: sam_paine
future beachfront property in the Texas Hill Country!

Was some time earlier, and might be again. Probably won't be real soon, though. Long term investment.

19 posted on 10/28/2002 5:42:40 PM PST by RightWhale
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To: null and void; ruoflaw
Ohio also had the greatest infestation of cockroaches in world history, estimated at 1300 yrs ago. The roaches ate nearly every living thing and left the place barren for like 600 yrs. Very sad, but true.
20 posted on 10/28/2002 10:32:41 PM PST by Professional
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