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quote:Originally posted by Exodus A Yellowstone eruption will be explosive, throwing dust high up into the atmosphere which will block out the sun.
quote:Originally posted by OldManForgive my seismic ignorance but the recent quake to hit Indonesia (8.7 was it?) isn't any sort of indicator or trigger to such volcanic activity is it? Please say "no Tim you're a fool no go back to hiding under your rock!"
quote:Originally posted by ExodusThere were a lot of things on that programme that were geologically very accurate, they did overdo a few things which i thought was a bit crap.
quote:Originally posted by Deanwinfieldwhat would happen to the UK if the supervolcano errupted in New Zealand? I presume the initial erruption wouldnt reach us, but the dust cloud or anything?"There is no gravity, the earth just sucks"
quote:Originally posted by BassAs you no doubt know, Yellowstone sits on top of a "hot-spot"- the heated rocks produce a seismic low velocity zone beneath the Yellowstone area extending down into at least the upper mantle. A somewhat similar low velocity zone has been recently discovered beneath the UK- perhaps in time you'll have your own version of "Old Faithful" (though I'm sure folks in the UK will come up with a much more humorous and descriptive name for such a feature).Darn my computer skills, I seem to have lost the link to the article. Will post again when I find it.Found it at last http://dsc.discovery.com/news/briefs/20050502/britisles.html [Links inactive - To make links active and clickable, login or click here to register]
quote:Originally posted by BassActually, volcanos have the opposite effect- they cool rather than warm the earth. Explosive volcanism injects ash and dust high into the stratoshpere, increasing the earth's albedo which leads to cooling. Sulfur dioxide emitted during eruptions, also acts as a coolant. Historical explosive eruptions all have demonstrated cooling effects.Prediction is difficult, especially the future. -Niels Bohr
quote:Originally posted by BassI've not read much about the subsequent warming effect of eruptions- I'd be interested if you have any sources.
quote:These sulfate aerosols will also accelerate chemical reactions that destroy the ozone. Ozone destruction allows dangerous levels of ultraviolet radiation to reach the earths surface and can increase the risk of skin cancers. Mid latitude ozone levels reached their lowest recorded concentrations during 1992-93. The ozone hole over Antarctica became the largest ever recorded and in 1991 the ozone levels in the troposphere decreased in time with the Pinatubo aerosol arrival. Mt. Pinatubo 2001)Carbon dioxide is the main greenhouse gas that allows a warming of the Earth. Volcanic gasses that are added to the atmosphere by volcanic eruptions increases this greenhouse gas and thereby the greenhouse effect. Initially the gaseous products cool the Earth for a period of 1 to 3 years. After the cooling effect is removed the increased carbon dioxide remains to potentially increase global warming.
quote:Sulfur dioxide (SO2) is the main gas released by volcanoes that can affect climate in the short term. Chemical reactions that occur when SO2 reaches the atmosphere produce tiny sulfuric acid droplets called “aerosol.” Very energetic eruptions push the aerosol up into the stratosphere, the layer of the atmosphere from 10 to 50 km altitude (around 32,000 to 164,000 ft), where it inhibits the sun’s energy from reaching and warming the earth’s surface. Once in the stratospheric jet stream, the aerosol quickly encircles the globe. The microscopic droplets tend to remain aloft for months to years, promoting global cooling. In the longer term, huge volcanic eruptions can have another effect. The release of greenhouse gases, such as carbon dioxide, into the atmosphere can cause warming rather than cooling.