Super Eruptions

Considering the latest news and activity in Yellowstone and Mt Rainier, I thought this was a fitting time to post a thread on super eruptions, showing exactly what to expect.

On second examination, a lot of what I am about to post is probably NOT going to be very representative of exactly what is likely in the event of a supervolcano or supercaldera eruption... simply because none of what has historically been recorded IS BIG ENOUGH TO COMPARE.

However, here goes...

Krakatoa:
Magnitude of the 1883 Eruption of Krakatoa
The 1883 eruption of Krakatoa has been assigned a Volcanic Explosivity Index or VEI of 6 which rates as "colossal". To be assigned a VEI rating of 6, a volcanic eruption must have a plume height over 25 km and a displacement volume ranging between 10 and 100 km3 (cubic kilometers). Eruptions of this size occur only once every few hundred years on earth.
The total energy released by the four main events of the 1883 eruption was equivalent to 200 megatons of TNT. Most of this energy was released by the third paroxysmal explosion which has been estimated to be equivalent to an explosion of 150 megatons of TNT. To understand the magnitude of the Krakatoa explosion, it will suffice to say that the Hiroshima atomic bomb was only about 20 kilotons).




www.drgeorgepc.com...

Santorini:
Santorini today is a lush Mediterranean paradise consisting of several islands in a ring shape. Twenty-five hundred years ago, though, it was a single large island with a volcano in the center. The volcano blew itself apart in a massive explosion around 1500 B.C.

To understand the effect of such an explosion, scientists have compared it with the most powerful volcanic explosion in historic times. This occurred on the Island of Krakatoa in 1883. There a giant wave, or tsunami, 120 feet high raced across the sea and hit neighboring islands killing 36,000 people. Ash thrown up into the air blackened the skies for three days. The sound of the explosion was heard as far away as 3,000 miles.




rover.phy.uncwil.edu...

Toba:
(Last known supervolcano eruption)
Toba, Indonesia (72 000 BC)giant explosion causing ice age
One of the greatest eruption ever known, the 2 200 cu km of pulverised rock pumped into the atmosphere lowered temperatures by as much as 15�C in some regions and probably plunged an already cooling planet into the icy grip of the glaciers. The blast created Lake Toba in Sumatra.

home.global.co.za...

BIGGEST ERUPTIONS KNOWN


TOBA, Indonesia (72000BC) erupted 2200 cu km
CRATER LAKE, USA (2900 BC) erupted 100 cu km
TAMBORA, Indonesia ( 1815 ) erupted 40 cu km
SANTORINI, Greece (1650 BC) erupted 30 cu km (3000 atom bombs equivalent)
HUAYNAPUTINA, Peru (1600) erupted 20 cu km
LAKI , Iceland ( 1783 ) erupted 10 cu km
SANTA MARIA, Guatemala (1902) erupted 10 cu km
ILOPANGO, El Salvador (260BC) erupted 10 cu km
NOVA RUPTA, USA ( 1912 ) erupted 10 cu km
LONG ISLAND, Papua New Guinea(1660) erupted 10 cu km
KUWAE, Vanuatu ( 1425 ) erupted 10 cu km
PINATUBO, Philippines (1991) erupted 7 cu km
KRAKATAU, Indonesia ( 1883 ) erupted 6 cu km
HUDSON , Chile ( 1991 ) erupted 3 cu km
VESUVIUS, Roman Empire (79AD) erupted 2 cu km
Mt ST HELENS, USA (1980) erupted 2 cu km (500 atom bombs equivalent)

home.global.co.za...

The Toba Eruption was so powerful, research on Mitochondrial DNA indicates that it may have shaped the eventual evolution of the Human into different races (totally different take on racial evolution in humans)

It suprises me how many people here think that the Multi-Reigional theory makes more sense then the Recent African Origin Model. First off, they bring up the idea that if we arose from the same stock, how do we have diffrent races? Well first of all: geneticists no longer favor the concept of race. We are far too similar along Mitochondrial and Nuclear DNA lines to be grouped into descrete catagories of races. Our outward appearances are merely /developmental/ characteristics. Secondly, the major cause for the evolution of "races" most probably occured as the result of the Toba Explosion in Sumatra. Toba was supervolcano, and its eruption plunged the entire planet into a year of nuclear winter. The genetic evidance points to a botleneck of a population that once had hundreads of thousands of members to just a few thousand. Inotherwards, it almost brought about our extinction. We became isolated into small pockets, into nook and cranies of the world, and gene flow between these idividual groups was reduced for some time, especially the first year when so many died. This increased the variation within the human species. Each individual pocket took on characteristics of its own, the start of "race." Up until that time we largely remained a very monolithic species. Finally, populations in Africa today show that whitn the same clan, the gentic diffrences are quite extreme. It is for this reason that an African has more of a chance of finding an organ donor from someone totally not related to him then from someone more closely related to him. This means that Africa had to be the homebase with a large enough population mass to immigrate outward, and each of the roups that settled into Europ, the Middle East, Asia, bred among themselves since they had a lower population base, lowering the amount of variation whitn thier own groups. What people do not realize is that thier were two mass movements out of Africa. One was by Eve, ans anatomically modern humans. The other was by Homo Erectus (or Ergaster). We know that the previous movement out of Africa had indeed lead to new species. Homo Neanderthalis is one of them. If Mungo Man is /not/ related at the mitochondrial leval to anoyone of us, (and realize that evreyone else alive to date has) then either Mungo Man is a space alien, which I highly doubt, or perhaps he is an entirely seprate species that looks alot like us, derived from the Homo Erectus stock and gone extinct before Homo Sapiens arrived in Australia. The evidance in favor of the Recent African Orign Model, far outweight the Multi-Reigonal model. /And/ it makes more sense. Only those who do not know the basics of inhertiance and genetics would think the Multi Reigonal Model makes more sense.

exn.ca...

THE YELLOWSTONE CALDERA
The most recent caldera-forming eruption about 650,000 years ago produced a caldera 53 x 28 miles (85 x 45 kilometers) across in what is now Yellowstone National Park (Figure 2). During that eruption, ground-hugging flows of hot volcanic ash, pumice, and gases swept across an area of more than 3,000 square miles. When these enormous pyroclastic flows finally stopped, they solidified to form a layer of rock called the Lava Creek Tuff. Its volume was about 240 cubic miles (1,000 cubic kilometers), enough material to cover Wyoming with a layer 13 feet thick or the entire conterminous United States with a layer 5 inches thick. The Lava Creek Tuff has been exposed by erosion at Tuff Cliff, a popular Yellowstone attraction along the lower Gibbon River.

The eruption also shot a column of volcanic ash and gases high into Earth's stratosphere. This volcanic cloud circled the globe many times and affected Earth's climate by reducing the intensity of solar radiation reaching the lower atmosphere and surface. Fine volcanic ash that fell downwind from the eruption site blanketed much of North America. This ash layer is still preserved in deposits as far away as Iowa, where it is a few inches thick, and the Gulf of Mexico, where it is recognizable in drill cores from the sea floor.

Lava flows have since buried and obscured most of the caldera, but the underlying processes responsible for Yellowstone's tremendous volcanic eruptions are still at work. Eventually, another "bead" may be added to Yellowstone's 300-mile-long string of calderas, with global consequences that are beyond human experience and impossible to anticipate fully.


vulcan.wr.usgs.gov...

More info...

www.geology.sdsu.edu...