Magazine article Insight on the News

Volcanic Catastrophe-in-Waiting Is Redefining Big Bang Theory: Volcanologists Are Watching Ancient Calderas for Signs of Life - and Danger. Not from Lava Flows or Noxious Gases, but an Eruption That Could Disturb Planetary Weather and Destroy the Fragile Ozone Layer

Magazine article Insight on the News

Volcanic Catastrophe-in-Waiting Is Redefining Big Bang Theory: Volcanologists Are Watching Ancient Calderas for Signs of Life - and Danger. Not from Lava Flows or Noxious Gases, but an Eruption That Could Disturb Planetary Weather and Destroy the Fragile Ozone Layer

Article excerpt

Volcanologists are watching ancient calderas for signs of life -- and danger. Not from lava flows or noxious gases, but an eruption that could disturb planetary weather and destroy the fragile ozone layer.

Did T.S. Eliot get it wrong? The world may end with a bang after all -- and it would be a doozy

There's an unknown but real probability that a catastrophic volcanic eruption will lay waste to thousands of square miles of the planet and severely affect Earth's climate for years afterward -- perhaps centuries.

The problem is not from pipsqueaks such as Popocatepetl, the 20,000-foot cone whose recent belch blanketed Mexico City in ash. Nor is it from Soufriere Hills which, little by little, is chasing away inhabitants of Montserrat, a small British protectorate in the Lesser Antilles. Nor from any other of the world's 1,500 or so active volcanoes. Their disturbances essentially are local.

What's coming is much bigger, an event volcanologists believe could threaten everyone and everything on Earth. The threat is from giant calderas, depressions left behind by ancient volcanoes that erupted catastrophically hundreds of thousands or even millions of years ago. Some of these calderas are still quite alive, at the moment only sleeping.

The problem is, scientists say, the scale is so large that no one really knows what the global effects will be.

Dozens of such sites dot Earth's surface, although many are unrecognizable. The most familiar -- and most benign -- is known as Pele, the goddess of fire and creation responsible for the Hawaiian Islands. In geologic terms, Pele is a "hot spot," a kind of periodic volcanic geyser.

Hot spots are enormous magma chambers that lie deep within the lithosphere, part of Earth's semimolten mantle. Over time, gas pressure builds at the top of the chamber and breaks through the crust. The result: a devastating eruption.

In the case of Pele, the outbursts haven't been catastrophic because Earth's crust is thin under the Pacific Ocean. Upwellings can reach the surface -- or in this case, the seafloor -- more easily. The periodic ejections became huge volcanic mounds -- the islands of Hawaii.

The same process works in more spectacular ways under the thicker continental plates. There, the pressure builds for long periods. Sooner or later, it punches though the 20 or so miles of continental crust as easily as a pushpin through corkboard.

Such a hot spot underlays the continental United States. It also happens to be one of the most popular tourist spots in America: Yellowstone National Park. Visitors who flock to see "Old Faithful," the world-famous volcanically heated geyser, may not be aware that they are standing atop a gigantic bubbling cauldron.

Around 2 million years ago, an enormous plume of magma burst through Earth's crust at the Yellowstone site. The resulting explosion ejected about 2,500 cubic kilometers of material into the atmosphere and the surrounding landscape. Ash from the eruption spread over what now are 25 states, covering several thousand square miles as deep as 65 feet. By comparison, the havoc caused by the 1980 eruption of Mount St. Helens in Washington state resulted from a displacement of about 0.3 cubic kilometers.

Two other eruptions -- not as large, but still staggering in scale -- since have occurred at Yellowstone. …

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