Discussion in 'Current Events' started by swanny, Dec 31, 2004.

  1. swanny macrumors regular


    Nov 12, 2004
    The Megatsunami: Possible Modern Threat
    By Robert Roy Britt
    Senior Science Writer
    posted: 14 December 2004
    09:49 am ET

    SAN FRANCISCO -- Volcanic landslides that generate huge and devastating tsunamis tend to occur during historically warmer times on Earth, a new study suggests. Scientists don't know exactly why, but since the global climate is warming as you read this, the apparent connection was tossed out this week as a reason for scientists to be concerned about the threat now.

    Tsunamis are waves that race across the ocean without much fanfare but grow to frightening proportions when they reach land. The waves are deep, and while they may appear just a few inches or feet tall on the open ocean, they can soar to the height of a multi-story building as they are forced upward near the shore.

    A tsunami can be generated by the sudden uplift of the seafloor in an earthquake, or by the paddle-like effect of a landslide crashing into the sea from, say, an island volcano. Yet while quake-generated tsunamis have been observed from their genesis to the disastrous end, scientists have never witnessed a significant open-ocean tsunami generated by a landslide.

    Evidence exists at various locations around the world for megatsunamis, as scientists call the largest of these events. They seem to occur every 100,000 years or so, said Gary McMurtry of the University of Hawaii.
    How Tsunamis Work

    Click to Enlarge

    These monsters can be hundreds of feet tall and, depending on local topography, race miles inland.

    One controversial event, about 110,000 years ago, appeared to create a 1,600-foot wave in Hawaii. Yes, you read that right: Nearly one-third of a mile, or about half a kilometer.

    But the evidence -- marine fossils way up there where there's no sea -- is controversial. Perhaps the islands have been rising and carried the fossils up, critics suggest.

    McMurtry's team looked at marine fossils at the Kohala volcano on the main island of Hawaii, which is known to be sinking about an inch per decade. The fossils simply could not have started at a lower elevation, McMurtry said Monday at a meeting of the American Geophysical Union held here. A submarine landslide from the giant Mauna Loa volcano has been dated to the same time and, the thinking goes, caused the tsunami.

    McMurtry and his colleagues also re-examined evidence for a tsunami that may have struck Bermuda and other locations in the Atlantic 420,000 years ago.

    Scientists agree that submarine landslides caused by the collapse of island volcanoes -- think of the destruction of Mount St. Helens -- could generate these megatsunamis. Evidence for such landslides can be found in topography scans of seafloors around various island volcanoes, McMurtry points out.

    "These giant landslides seem to occur during periods of higher than normal sea level -- like we have now," he said.

    High sea levels tend to correspond with wetter climates, he said. What this has to do with landslides is not known. But perhaps, McMurtry figures, excess rainfall can serve as a trigger for the cleaving of a volcano-in-waiting.

    That might all sound like a lot of logic leaps, and McMurtry is the first to admit there isn't enough data to figure out whether global warming and tsunamis are correlated. But there is some independent thinking that supports the notion.

    Peter Cervelli, of the Alaska Volcano Observatory, has studied the Hawaiian volcanoes and is not involved in McMurtry's work. Cervelli said it's possible that water during extended wet periods seeps down into natural faults on the flanks of a volcano -- volcanoes are known to be more porous than other land areas -- precipitating a collapse by "bringing it closer to failure."

    And in other work, Emily Brodsky of the University of California, Los Angeles has modeled the friction involved in huge volcanic landslides. She agrees that it's possible that higher rainfall amounts could make a precarious situation more slippery.

    So should we worry? "Maybe," says McMurtry. He thinks that a tsunami, which can race across an entire ocean in a matter of hours, is a real threat to urbanized coastlines. Other experts agree that a large tsunami would be bad news for, say, Los Angeles or New York City. And tsunamis are not parochial. One originating in Alaska in 1964 killed people in California and generated damaging surges clear down in Chile.

    McMurtry believes the threat is greater than from an asteroid impact, but asteroid research has managed to lure more funding. More money should be spent to monitor the stability of oceanic volcanoes, McMurtry argues.

    "Mauna Loa is as big as it's ever been, so the energy is there" for a giant submarine landslide, McMurtry said. He's even attached some odds to the threat: "The probability of a megatsunami in Hawaii in the next 10,000 years is about 50 percent."
  2. swanny thread starter macrumors regular


    Nov 12, 2004
    Now what?

    Well since we're dealing with a rather large time frame (10,000 years or so)
    does this mean the correlation and "correction" between
    global warming and tsunamis has now been mitigated?
    The earth's mechanism seem's to have taken the "problem"
    (global warming) and "dealt" with it in it's historical fashion.
    Okay ..... so far so good or so......!
    But now what? It seems the problem was perhaps adjusted
    at the "weakest link' aspect and a lot "desparately poor" people
    paid the price of it. Pay the price because certain "advantaged"
    people refused to "admit' that there was even a problem.
    Oh well or not?
    Well I don't know? I don't know everything
    and do I have to do everything for you?
  3. wdlove macrumors P6


    Oct 20, 2002
    The threat of a megatsunami is quite a scary thing to contemplate. It seems that now there is increased concern for a tsunami to occur at any time and not just the Pacific. When they mention that a tsunami could occur in the Atlantic and reach 10 miles inland. Mentioning that really hits home, if that occurred in my lifetime, it would reach my house. :eek:
  4. swanny thread starter macrumors regular


    Nov 12, 2004


    Well its a question of probablities

    The one we just had was sort of a "medium" class.
    The really big ones are few and far between so they say.
    But this one was triggered by a richter 9 earthquake
    which they say is 1000x the strength of the one
    that hit Frisco in the 1980s.

    But the supposed correlation between them and global warming
    means in a sense that humanity might factor in to
    if we by our actions are excessively contributing to the warming.

    My theory is that the weight of the extra sea water
    from the melting polar caps exerts pressure on the tectonic
    plates which then "give" or adjust.

    This latest underwater quake is said to have "compacted"
    or "consolidated" the Earth somewhat which itself has
    a minute effect on the rotation of the planet speeding it up but
    life is for learning.

    Maybe it has adjusted the problem for the next 1000
    years and maybe not. Interesting how that works
    though. I wonder if its a "cycle" of sorts.
    The sort of contraction and expansion of the plates
    to adjust for temperature fluctuations on the surface
    and in the "hydrological cycle" and such.
  5. altair macrumors regular

    Nov 22, 2002
    Seattle, WA
    Sorry, not to be pretentious, but thought i would shed some light with what knowledge i have, i might be wrong about some stuff though :p

    I have a 4 year degree in geology and am currently working in the field.

    Your right, each increase in a whole number indicates 1000x the strength, so a 8 is 1000 times stronger than a 7. I read somewhere, cnn i think, that the amount of energy released in this quake was equivalent to about 38 billion tons of TNT...insane.

    The one thing that i was thinking, there have been theories around about volcanism affecting the climate, both contributing to warming and cooling, so it makes sense, theoretically, that increases in volcano activity, and growth, would cause more landslides, and the emissions from the volcano could be causing the global warming. ::shrug:: just a different side of the coin.

    I just dont see why the earth getting warmer would cause more underwater landslides...

    I really dont think that the weight of the extra sea water would cause enough pressure for it to make any difference to the plates.

    One thing to remember, is that these plates are moving all the time, very slowly yes, but most of them move enough to be measured. So if they plates become locked, the pressure keeps building and building, and eventualy the locked area breaks, allowing the plates to move.

    Think ya got this one right

    Would probably take a pretty huge temperature change for the plates to contract or expand.

    Im curious if the plates are going to lock again, or keep sliding smooth. That will pretty much let us know if its going to happen again in the semi-near future.

    Hope i didnt sound like a prick in any part of this, sorry if i did :eek:
  6. swanny thread starter macrumors regular


    Nov 12, 2004

    My apologies for my anger...
    Let us then deal with the "FACTS'
    and the "Realities".
    What are they then?
    What are the facts and realities at this time?
    Monday January 3, 2005 on the Planet Earth
    in the Milky Way Galaxcy.
    Speak not of propositions then
    but of the "Actions" we can take,
    and let us to act with grace, calm and foresight
    less we make matters worse.

    And thankyou for your reply and contribution though
    I think some of what we "both" have said is somewhat
    besides the point. Millions of people have been
    "traumatized" and trauma is problematic and
    expensive at times.
  7. angelneo macrumors 68000

    Jun 13, 2004
    I just recently watched a documentary about these megatsunami. They mentioned that the greatest tiger wave generated by earthquake can only reached about 10 metres or so (maybe 15).

    I vaguely remembered that they mentioned documenting a megatsunami in the 1950s with witnesses talking about waves that are 10/20 times of the normal tsunami. (couldn't really remember the exact details as I was doing some other thing at the same time)
  8. swanny thread starter macrumors regular


    Nov 12, 2004

    I think, in a way, what we have to do, in regards to the quake and tsunami event
    of Boxing Day 2004 and its aftermath, is to resist the temptation to run away. To run away like those millions had to do in their hour of despair. To run and try to escape from what is and was quite simply a natural phenomenon

    Yet this simple natural event, so dwarfs our earthly scope and grasp that we can, if allowed, become awed, transfixed and hypnotized by its sheer magnitude and power. Caught up in this not so common, on our scale and terms, natural process which seems to seize and paralyzes our minds and imagination.

    We must dig deep though and find a resolve and strength to withstand its seemingly dark spell and stay rooted in our faith, reason and meaning for being, living and doing.

    Yet we cannot, on the other hand, simply ignore it either and the millions that it swept over the side into its waters of loss, pain and confusion. No we instead must, stand firm and tall and pull to ourselves, safety and comfort, those that stood upon the front lines and took its, not wrath, but of the shock of its unannounced and unexpected natural occurrence. An occurrence that perhaps bodes as a disaster to us, but is simply in some sense a reoccurring and natural effect for our planet.

    So then, can we thus now stand firm and respectful in our humanhood and this Earth we call home and accept and overcome its natural reality and effects together?
  9. Sir_Giggles macrumors 6502a


    Dec 18, 2003
    I think a megatsunami is the work of scare-mongers. Hey, you gotta sell ads and subscriptions, so why not capitalize on everyones' fears?
  10. altair macrumors regular

    Nov 22, 2002
    Seattle, WA
    I dont understand, but thats ok, sorry again if i pissed ya off.
  11. wdlove macrumors P6


    Oct 20, 2002
    There is no reason to be sorry or embarrassed. Your post is very informative and knowledgeable. Your opinion based on knowledge is appreciated.
  12. angelneo macrumors 68000

    Jun 13, 2004
    I don't really think so although it really sounds like it is capitalizing on the current situation. Here's the BBC documentary, made in 2000, which I saw:


    According to the documentary, the documentated mega-tsunami happened in 1958 in a remote bay in Alaska resulting in 500 metres high waves.

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