Toba: Super Volcano in Sumatra, page 1
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Topic started on 3-1-2005 @ 03:22 PM by PistolPete
Apparently Sumatra has a super volcano located very close to where all the earthquakes took place. It erupted 74,000 years ago and was the largest eruption in the last 200,000 years.

www.bbc.co.uk
The last supervolcano to erupt was Toba 74,000 years ago in Sumatra. Ten thousand times bigger than Mt St Helens, it created a global catastrophe dramatically affecting life on Earth. Scientists know that another one is due - they just don't know when... or where.....

.....Climatologists now know that Toba blasted so much ash and sulphur dioxide into the stratosphere that it blocked out the sun, causing the Earth's temperature to plummet. Some geneticists now believe that this had a catastrophic effect on human life, possibly reducing the population on Earth to just a few thousand people.


Toba on the map:


Where the earthquakes took place:



The Toba Caldera fault zone:



More info on the Toba Caldera:

Toba caldera produced the largest eruption in the last 2 million years. The caldera is 18 x 60 miles (30 by 100 km) and has a total relief of 5,100 feet (1700 m). The caldera probably formed in stages. Large eruptions occurred 840,000, about 700,000, and 75,000 years ago. The eruption 75,000 years ago produced the Young Toba Tuff. The Young Toba Tuff was erupted from ring fractures that surround most or all of the present-day lake.

Comparison of volumes produced by some of the greatest volcanic eruptions. The Young Toba Tuff has an estimated volume of 2,800 cubic kilometers (km) and was erupted about 74,000 years ago. The Huckleberry Ridge Tuff, erupted at Yellowstone 2.2 million years ago, has a volume of 2,500 cubic km. The Lava Creek Tuff, erupted at Yellowstone 600,000 years ago, has a volume of 1,000 cubic km. The May 1980 eruption of Mount St. Helens produced 1 cubic km of ash. Not shown is the Fish Canyon Tuff of the San Juan Mountains of Colorado. The Fish Canyon Tuff was erupted 27.8 million years ago and has an estimated volume of 3,000 cubic km.

The volume of the youngest eruption is estimated at 2,800 cubic km, making the eruption the largest in the Quaternary. Pyroclastic flows covered an area of at least 20,000 square km. Up to 1200 feet (400 m) of Young Toba Tuff is exposed in the walls of the caldera. On Samosir Island the tuff is more than 1800 feet (600 m) thick. Ash fall from the eruption covers an area of at least 4 million square km (about half the size on the continental United States). Ash from the eruption has been recovered from deep-sea cores taken in the Bay of Bengal and in India, roughly 300 miles (500 km) inland (1,900 miles, 3100 km from Toba). Rose and Chesner suggested the ash may have reached central Asia and the Middle East. Ninkovich and others (1978) estimated of the height of the eruption column to be 30 to 50 miles (50 to 80 km) for the Young Toba Tuff. Rose and Chesner, after a study of the shapes of the ash shards, concluded this estimate was too high by a factor of 5 or more.


I'm quite certain that the earthquakes and the supervolcano are quite unrelated, but it's interesting any way.

Sorry for all the quoting but I'm no geologist.


reply posted on 5-1-2005 @ 01:01 AM by PistolPete
Originally posted by Off_The_Street
Pistol Pete, that's a good post indeed. If you're interested in old volcanoes in general and Java/Sumatra ones in particular, you might want to get a book by David Keys called: "Catastrophe: An Investigation into the Origins of Modern Civilization" (www.amazon.com...).

I think you'd really enjoy it.


Cool off_the_street, I'll look into it! Reading the description it sounds like something up my alley.

I just got done sifting through: Guns, Germs and Steel: The Fates of Human Society, by Jared Diamond. How we got where we are I believe is just as important as where we're going.



reply posted on 5-1-2005 @ 11:55 AM by Banshee
Originally posted by specialasianX
but the volcano used as a example there has erupted in the last 150 years so i think we're safe from that one


I believe you're thinking of Krakatoa, not Toba.
Toba is on a much larger scale than Krakatoa, which is a huge volcano to begin with.

A full eruption of Toba would make Krakatoa look like a sneeze, unfortunately.


reply posted on 5-1-2005 @ 02:31 PM by E_T
Originally posted by Banshee
I believe you're thinking of Krakatoa, not Toba.
Toba is on a much larger scale than Krakatoa, which is a huge volcano to begin with.
Krakatoa... that small backyard campfire.

Total energy release of eruption was only ~200 Mt altough third and last "bang" equivalent to ~150 Mt caused generally over 10 meters high tsunami and over 30 meters in "best" places while destroying most of island. (that which didn't fly to the sky collapsed to caldera)
Also shockwaves of explosion were detected only seven times with barographs when they made "couple" rounds around the globe.

And Lang and Verlaten (with Krakatoa) were propably parts of bigger island which collapsed to caldera in bigger eruption in the past. (compare to Santorini)


www.drgeorgepc.com...


reply posted on 13-4-2005 @ 06:00 AM by Ulvetann
www.abovetopsecret.com...

An post on this theme is already running...

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