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Friday, September 15, 2006

Volcanoes and supervolcanoes

Volcanoes

Out of sight, out of mind. That's mostly how I think of volcanoes, if I think of them at all. But after doing a little reading, maybe I need to be a little more respectful of these amazing phenomena.

The earth currently has roughly 2500 volcanoes, 1511 of which have erupted in the last 10,000 years.

The record holder for the largest volcanic eruption in recorded history goes to Tambora (in Indonesia). Folks could hear it 1775 km away in Benkoelan (on Sumatra).

Some volcanos have been active for hundreds or even thousands of years. Consider the following:

  • Kilauea in Hawaii has been erupting continuously since January 1983; 74 eruptions have been recorded from this volcano since 1790.
  • Mauna Loa, also in Hawaii, has had 40 eruptions since the mid-1700s.
  • Erta Ale in Ethiopia has been erupting for the past 30 years.
  • Japan's first recorded eruption of Sakura-jima was in 709 AD; it has currently been erupting since 1955.
  • Also in Japan, Aso has had 167 eruptions, many of them explosive, since 533 AD.
  • Colima, in Mexico, has had 52 eruptions since folks started writing it down in 1560.
  • Santa Maria in Guatamala has been erupting since 1922
  • Masaya in Nicaragua's first documented eruption was in 1524 and it's been erupting almost continuously since then. That's almost 500 years.
  • Nyiragongo in Zaire, created alava lake for 50 years which finally ended in 1977.
  • Piton de la Fournaise on Reunion Island has had 153 eruptions since 1640 when people began documenting them.
  • Marapi in Sumatra, Indonesia, has had 59 eruptions since 1770, with the current one beginning in 1987.
  • Cotopaxi in Ecuador, has had 59 eruptions since 1532 and has produced the most mudflows (27).
  • Villarrica in Chile has had 53 eruptions since 1558.
  • Erebus in Antarctica has been erupting since 1972.
  • But the granddaddy of them all, at least in terms of longevity, is Etna in Italy. Etna has been erupting for (are you ready for this?) over 3500 years!

Supervolcanoes

There are about a dozen supervolcanoes waiting for an opportune moment to blow. Probably the most famous is the Yellowstone supervolcano which erupted around 630,000 years ago. That eruption is considered to be the largest and most cataclysmic in the geologic record.

Bad news: Yellowstone National Park sits on one of the most geologically active spots on the planet, and all indications are that another supervolcano is festering beneath its surface. If it blows, it will produce enough debris to cover the entire United States with a good 5 inches of lava, bring on an extended winter and probably even take mankind (and lots of his furry pals) to extinction.

Good news: Professional geologists who are studying it are not concerned that it's going to happen any time soon (geologically speaking). The last supervolcano erupted only 74,000 years ago and that is like yesterday in geologic time. We've probably got at least another half a million or so years before we need to panic.


Reference:
Volcanoes: University of North Dakota
Supervolcanoes: ABC news

2 Comments:

Blogger PJ said...

What a wonderful blog! I'm an author, and am always interested in informative sites such as yours. I'll be back, that's for sure!

7:51 AM  
Blogger chris humphrey said...

Thanks, PJ. I hope you will make this a regular stop. I never know what the next day's topic will be, so I'll be as surprised as you to see what crops up.

Many years ago newspapers would print odd little bits of information as fillers (and total non-sequiters), and as a kid I used to cut these out and save them. My favorite one was "octopus eggs are small, numerous and tear-drop shaped."

8:33 AM  

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