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The Earth Quake Thread

topic posted Fri, September 9, 2011 - 6:57 PM by  Celestine
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A 6.4 earthquake hit Vancouver Canada today.

earthquake.usgs.gov/earthqua...05rsj.php

After experiencing the quake that hit Virginia I find the amount of quakes and intensity of quakes interesting.
posted by:
Celestine
Pennsylvania
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  • Re: The Earth Quake Thread

    Wed, September 28, 2011 - 12:55 PM
    The melting ice caps are producing an above average amount of Earthquakes... cites???
    "( I know I've posted this before and some people on this tribe said that I was full of shit so I left it but sure enough, the data is adding up in favor of the link between mealting global ice sheets and more faults starting to become unstable)"

    As ice sheets melt, they can release pent-up energy and trigger massive earthquakes, according to new study...

    The study showed that earthquakes are "suppressed in presence of the ice and promoted during melting of the ice," said study leader Andrea Hampel of the Ruhr University Bochum in Germany.

    Hampel and a colleague had earlier found evidence that the shrinkage of a huge lake at the end of the last ice age had triggered a series of large earthquakes in Utah.

    The new study shows this can happen even along faults that are normally quiet and are not prone to slip.

    More cites are abundant online, you can do the searching yerselves :)
    • Re: The Earth Quake Thread

      Wed, September 28, 2011 - 9:30 PM
      >"As ice sheets melt, they can release pent-up energy and trigger massive earthquakes, according to new study... "

      No argument there. The only thing I'd change is using the word 'massive.' The resultant quakes are more often than not local/regional and none that I'm aware of have ever been above a 3.5 at the hypocenter.

      BTW, in the geophysics community there's a word for what you describe. It's known as 'isostatic rebound' or 'post-glacial rebound' the terms is most often referred to in papers about glacial geomorphology.

      See; en.wikipedia.org/wiki/Isostasy

      • Re: The Earth Quake Thread

        Thu, September 29, 2011 - 7:13 AM
        @Tant "The only thing I'd change is using the word 'massive.'"

        Sorry, but I didn't write the research, I was just quoting what I found in the research papers from the study of leader Andrea Hampel of the Ruhr University Bochum in Germany.

        ""
        Wiki, "The formation of ice sheets can cause the Earth's surface to sink. Conversely, isostatic post-glacial rebound is observed in areas once covered by ice sheets that have now melted, such as around the Baltic Sea and Hudson Bay. As the ice retreats, the load on the lithosphere and asthenosphere is reduced and they rebound back towards their equilibrium levels. In this way, it is possible to find former sea cliffs and associated wave-cut platforms hundreds of metres above present-day sea level. The rebound movements are so slow that the uplift caused by the ending of the last glacial period is still continuing.

        In addition to the vertical movement of the land and sea, isostatic adjustment of the Earth also involves horizontal movements. It can cause changes in the gravitational field and rotation rate of the Earth, polar wander, and earthquakes."

        *===...


        One has to ask themselves, to what manner of change will the current magnitude of ice melt, that is happening on a grand scale across the globe, will have in the current situation where tousands of tons of ice is melting every day across the globe?
        • Re: The Earth Quake Thread

          Thu, September 29, 2011 - 7:21 AM
          It's kind of funny because we see a reduction in the magnetic field around the planet and this can be directly linked to the melting ice too...
          • Re: The Earth Quake Thread

            Thu, September 29, 2011 - 11:17 AM

            >"a reduction in the magnetic field around the planet and this can be directly linked to the melting ice too... "

            Um, you need to provide some serious ass citations for that statement because I'm smelling all kinds of 'wrong' with it.
            • Re: The Earth Quake Thread

              Thu, September 29, 2011 - 11:51 AM
              Tant, I'm surprised, in 'your' wiki link and my post of the very instance where Wiki states such...
              @Tant, "Um, you need to provide some serious ass citations for that statement..."

              Wiki, "In addition to the vertical movement of the land and sea, isostatic adjustment of the Earth also involves horizontal movements. It can cause changes in the gravitational field and rotation rate of the Earth, polar wander, and earthquakes."

              or else Wiki is wrong, OMG we couldn't have that now could we? :)))

              I never knew there was/had ever been a correlation between such but 'somebody' stated these facts in Wiki, maybe we should ask for 'cites' in that article backing up such a stance?
              • Re: The Earth Quake Thread

                Thu, September 29, 2011 - 2:44 PM
                The gravitational field that you mention in your above example is indeed possible. Happens when the dense, compressed becomes less dense as the overburden releases pressure. On an almost imperceptible (but measurable) scale the field does change. What it doesn't do is give rise to a shifting or flipping of the magnetic poles as some people in this tribe have suggested in past posts. The polar wandering mentioned is wandering of the Earth's geographical north and south pole. I didn't catch any reference to magnetic wandering which I'd be skeptical about.