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Lonestar
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AECCP Dark Lord of the Sith
Aug 2000
time: 00:30
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Or Geology-types like him. Fear the Yellowstone Caldera.
I have put together bits and pieces of information as accurately in accordance to the latest theories, discoveries, and observations that I am familiar with or aware of to date. I used some of the more publicized volcanoes of the past few years to describe recent, smaller magnitude events; and the famed eruptions of the ages to describe to larger scale magnitude events.
A scale has been created to determine the magnitude of volcanic eruptions. This scale is known as the Volcano Explosivity Index or VEI. The range of this scale is from zero magnitude to eight. Therefore your weakest explosive volcanic activity will be represented from 0 to your most mega-colossal at 8 as in the following examples:
-- The Hawaiian volcanoes such as Kilauea are nearly in constant eruption throughout their active existence on the geological timescale. However, their magmas are not very gacious: only emitting 1000s m³ volumes of CO2, SO2, and volcanic material levels daily. Ash and steam plumes may reach 100m at times. These eruptions are classified at VEI-0 magnitude and are described as non-explosive. Usually associated as Hawaiian.
Pu`u `O`o, among several other vents on the flanks of Kilauea, are producing lava flows on the surface and through tubes right now. Some of these flows are presently reaching the Pacific ocean and creating new Hawaiian coastline.
-- A minor to moderate explosive steam or ash exhalation (such as the many that can be presently viewed by internet cams almost daily at Stromboli, Popocatépetl, Colima and Etna) can be listed under VEI-1 magnitude. They release CO2, SO2, and volcanic materials in the 10,000s m³ and ash-steam plumes ranging from 100-1000m high. These occur at a multitude of restless volcanoes around the world on a daily basis. Incandascent material ejection can be accompanied in these magnitude eruptions. Kilauea occasionaly reaches this level in its constant state of activity. This level is catagorized as gentle eruptivity. Usually associated as Hawaiian/Strombolian type eruptions.
-- VEI-2 magnitude eruptions are explosive episodes that can be occasionally viewed (with the lucky eye) at Popocatépetl and Colima, or far more frequently at Mount Etna which are currently occuring on a weekly basis. Many other volcanoes such as Mount Mayon in the Philippines, Nyamuragira and Nyiragongo in Africa (among the more publicized) have exibited eruptions at this level numerous times over the past few years as well. Incandascent materials of lava are often ejected during eruptions of this magnitude. Eruptive volume is in the 1,000,000s m³ and ash plumes reach 1-5 km in altitude. These are usually associated with Strombolian/Vulcanian eruptions.
-- VEI-3 is catagorized as severe. Mount Mayon had a VEI-3 magnitude eruption on June 24th, 2001. These are accompanied by significant ejection of incandascent materials, steam and ash. Eruptive volume of this magnitude reaches levels into 10,000,000s m³ and ash plumes can reach 3-15km in altitude. Pyroclastic flows can and do occur during these eruptive episodes. These eruptions are typically Vulcanian in nature.
-- VEI-4 level eruptions are much less frequent but cataclysmic in scale. Several volcanoes are currently being monitored closely for fear of an eruption of such magnitude. Several of the volcanoes listed above are frequently on high alert for the possibility reaching this scale of eruptivity, from as many as a few months to a few days warning. Large amounts of incandascent materials will be ejected, accompanied by large pyroclastic flows that can be very destructive in nature. This scale can cause a great deal of destruction and loss of life near populated areas. Eruptive volume of this magnitude reaches levels of 100,000,000s m³ and can produce ash plumes from 10 to 25 km in altitude. Galunggung in 1982 had an eruption of this magnitude. These eruptions are Vulcanian/Plinian in nature.
-- VEI-5 are even less frequent but paroxysmal in scale. Mount Saint Helens on May 18th, 1980 had an eruption of this magnitude. It had over 50 times the explosive energy as the atomic bomb dropped on Hiroshima. Extremely destructive eruptions that can lay to waste areas of up to 300km² in size. Eruptive volume of this magnitude reaches levels of 1 to 9.9 km³ and produces ash plumes over 25km in altitude. Eruptions are Plinian in nature.
-- VEI-6 magnitude eruption are colossal in scale. They may only occur on average a few times per century. Pinatubo, Katmai and Krakatau are the last three to reach such scale. Of these, Krakatau's eruption in 1883 was the largest. It destoyed the entire island and created tsunamis that devestated surrounding coastlines and pumped so much volcanic material into the atmosphere it cause the earth's average temperatures to cool 1.2 degrees celsius over a period of 4-5 years, making summer nearly non-existant in New England and Europe during the post-eruption year. Eruptive volumes of this magnitude reaches levels in the 10 to 99.9 km³ and ash plumes will surpass 35km. Volcanic dust can be carried by the tropical easterlies and jetstreams in northern and southern hemispheres around the earth a multitude of times before it finally settles. Such magnitude eruptions are Plinian/Ultra-Plinian.
-- VEI-7 magnitude eruptions are super-colossal in scale. They can wreak havoc on climates around the globe. Tambora in 1815 is the largest eruption in modern historical times. It erupted 100 cubic km of ash and produced a column over 50 km high. It caused global cooling and the year without a summer in 1816. Crop failure caused widespread famine. There is insufficiant data to dictate just how great the temperature changes were on a global scale, but we have documentation of severe winters in New England and Europe from 1815 through the early 1820s that can be in theory associated with the dramatic impact such significant amounts of eruptive volume would have inflicted on our atmosphere. VEI-7 eruptive volume will reach between 100 and 999.9 km³ and ash will surpass 35km in altitude. Volcanic dust will circle the earth for years. Eruptions of this magnitude are Ultra-Plinian.
-- VEI-8 magnitude eruptions are almost unfathomable in scale. Commonly known as "Super Volcanoes," they are mega-colossal in nature. They can literally wipe out everything changing the course of life. They are on a scale with astoroids and comets in destruction. They are so enormous in eruption they leave massive depressions on the surface of the earth 100s km² in size. These calderas can eject 1,000+ km³ of volcanic materials throughout the atmosphere and devestate on a global scale. Eruptions so powerful that materials can literally be blown into orbit. Toba Caldera in Sumatra was the last "Super Volcano" eruption around 74,000 years ago. And there is scientific evidence, both geologic and genetic still being researched and pieced together that may eventually prove this eruption to have had an adverse effect on the population of modern man -- possibly even pushing humans to the brink of extinction. Yellowstone Caldera in North America may hold the record for the largest of these mega-colossal volcanic eruptions in the past three million years. Where as Toba Caldera's eruption may have been 10,000 times more powerful than Mount Saint Helens eruption on May 18th, 1980, Yellowstone has produced eruptions over 15,000 times greater. Eruptions of such horrific and apocolyptic scale, mankind can hope to never witness (again). If our species is to continue life on this earth for 10,000s of years into the future, we are likely to have to deal with another of these monsters. These eruptions are Ultra-Plinian.
According to the United States Geological Survey's Yellowstone Volcano Observatory, Yellowstone Caldera has sustained eruptions of VEI-8 magnitude 2.0, 1.3 and 0.6 million years ago with intermittent eruptive periods of lesser magnitudes. It is fueled by a hot spot that in theory has existed for an even greater geological time period. It may very well be the largest and oldest hot spot on earth. Only because of the great mass and thickness of the North American continent, it's eruptions are "plugged" or "capped" for much longer periods of time than say a hot spot that fuels the Hawaiian Island chain, whose magmas only have to penetrate the much thinner ocean floor crust. This effect of "capping" in theory could explain the mega-colossal eruptions when the reservoirs of magma can no longer be contained within the crust. Where the crust in turn from the heat of the magma melts magnifying the effects, increasing the amount magma even more in the reservoir until the apocolyptic scale eruption ensues.
This same hot spot has remained fixed as the North American continent has slowly slid at a rate of 5-6cm a year to the WSW. The geological evidence is provided by the now extinct calderas that run in a straight line from just WSW of Yellowstone, through Idaho, into southeastern and southern parts of Oregon. These millions of years old calderas are responsible for the massive basaltic floods and lava fields that make up a large part of the Idaho, Oregon, Washington countryside, and extreme northern portions of Nevada and California. A large portion of the Cascade Range's magestic volcanic structures were constructed possibly during and certainly on top of the remnants of these enormous and ancient flows. The Columbia River has cut deep gorges and canyons into these ancient lava fields allowing for closer geological inspection. One of these basaltic floods was among of the largest in global geological history. With all this geological evidence, we can therefore assume (that word annoys me too, Don) this same hot spot that feeds Yellowstone, with it's extraordinarily long geological presence, will continue its activity well into the near to distant future. It appears eruptions of VEI-8 magnitude will occur either in Yellowstone Caldera or a new caldera by this hotspot again. The question that remains to be answered is... when?
The USGS website also mentions the "Supervolcano" in Long Valley (Eastern Cali) is overdue.
I'm screwed.
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st_swithin
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10069
Nov 2002
time: 05:30
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Do we have any friends in Montana?
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st_swithin
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10069
Nov 2002
time: 05:30
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Don't we still have the wheelbarrow and Holocaust cloak from last time?
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st_swithin
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10069
Nov 2002
time: 05:30
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FABULOUS!!!!
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All times are GMT. The time now is 05:30.
Apolyton Time is 00:30. |
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04-09-2003 06:09
Smiley 
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