Super Volcano Will Challenge Civilization, Geologists Warn

The eruption of a super volcano "sooner or later" will chill the planet and threaten human civilization, British scientists warned Tuesday.

Several volcanoes around the world are capable of gigantic eruptions unlike anything witnessed in recorded history, based on geologic evidence of past events, the scientists said. Such eruptions would dwarf those of Mount St. Helens, Krakatoa, Pinatubo and anything else going back dozens of millennia.

"Super-eruptions are up to hundreds of times larger than these," said Stephen Self of the United Kingdom’s (U.K.) Open University.

"An area the size of North America can be devastated, and pronounced deterioration of global climate would be expected for a few years following the eruption," Self said. "They could result in the devastation of world agriculture, severe disruption of food supplies, and mass starvation. These effects could be sufficiently severe to threaten the fabric of civilization."

Self and his colleagues at the Geological Society of London presented their report to the U.K. Government's Natural Hazard Working Group.

"Although very rare these events are inevitable, and at some point in the future humans will be faced with dealing with and surviving a super eruption," Stephen Sparks of the University of Bristol told LiveScience in advance of Tuesday's announcement.

The warning is not new. Geologists in the United States detailed a similar scenario in 2001, when they found evidence suggesting volcanic activity in Yellowstone National Park will eventually lead to a colossal eruption. Half the United States will be covered in ash up to 3 feet (1 meter) deep, according to a study published in the journal Earth and Planetary Science Letters.

Explosions of this magnitude "happen about every 600,000 years at Yellowstone," says Chuck Wicks of the U.S. Geological Survey, who has studied the possibilities in separate work. "And it's been about 620,000 years since the last super explosive eruption there."

Past volcanic catastrophes at Yellowstone and elsewhere remain evident as giant collapsed basins called calderas.

A super eruption is a scaled up version of a typical volcanic outburst, Sparks explained. Each is caused by a rising and growing chamber of hot molten rock known as magma.

"In super eruptions the magma chamber is huge," Sparks said. The eruption is rapid, occurring in a matter of days. "When the magma erupts the overlying rocks collapse into the chamber, which has reduced its pressure due to the eruption. The collapse forms the huge crater."

The eruption pumps dust and chemicals into the atmosphere for years, screening the Sun and cooling the planet. Earth is plunged into a perpetual winter, some models predict, causing plant and animal species disappear forever.

"The whole of a continent might be covered by ash, which might take many years -- possibly decades -- to erode away and for vegetation to recover," Sparks said.

Yellowstone may be winding down geologically, experts say. But they believe it harbors at least one final punch. Globally, there are still plenty of possibilities for super volcano eruptions, even as Earth quiets down over the long haul of its 4.5-billion-year existence.

"The Earth is of course losing energy, but at a very slow rate, and the effects are only really noticeable over billions rather than millions of years," Sparks said.

The odds of a globally destructive volcano explosion in any given century are extremely low, and no scientist can say when the next one will occur. But the chances are five to 10 times greater than a globally destructive asteroid impact, according to the new British report.

The next super eruption, whenever it occurs, might not be the first one humans have dealt with.

About 74,000 years ago, in what is now Sumatra, a volcano called Toba blew with a force estimated at 10,000 times that of Mount St. Helens. Ash darkened the sky all around the planet. Temperatures plummeted by up to 21 degrees at higher latitudes, according to research by Michael Rampino, a biologist and geologist at New York University.

Rampino has estimated three-quarters of the plant species in the Northern Hemisphere perished.

Stanley Ambrose, an anthropologist at the University of Illinois, suggested in 1998 that Rampino's work might explain a curious bottleneck in human evolution: The blueprints of life for all humans -- DNA -- are remarkably similar given that our species branched off from the rest of the primate family tree a few million years ago.

Ambrose has said early humans were perhaps pushed to the edge of extinction after the Toba eruption -- around the same time folks got serious about art and tool making. Perhaps only a few thousand survived. Humans today would all be descended from these few, and in terms of the genetic code, not a whole lot would change in 74,000 years.

Based on the latest evidence, eruptions the size of the giant Yellowstone and Toba events occur at least every 100,000 years, Sparks said, "and it could be as high as every 50,000 years. There are smaller but nevertheless huge eruptions which would have continental to global consequences every 5,000 years or so."

Unlike other threats to mankind -- asteroids, nuclear attacks and global warming to name a few -- there's little to be done about a super volcano.

"While it may in future be possible to deflect asteroids or somehow avoid their impact, even science fiction cannot produce a credible mechanism for averting a super eruption," the new report states. "No strategies can be envisaged for reducing the power of major volcanic eruptions."

The Geological Society of London has issued similar warnings going back to 2000. The scientists this week called for more funding to investigate further the history of super eruptions and their likely effects on the planet and on modern society.

"Sooner or later a super eruption will happen on Earth and this issue also demands serious attention," the report concludes.

A volcanic island collapse will have several orders of magnitude more inherent and kinetic energy involved than any earthquake ever envisioned.

On what do you base this assertion? If you are referring to a mild earthquake, maybe. But when you are talking about a 9.0 on the richter scale earthquake, I think that you are wrong. A volcanic island collapse (and we are not talking about a total collapse with Cumbre Vieja) is a localized event involving a relatively finite volume of dirt and rocks that slide, with varying degrees of speed, into the sea. Now, if you really believe that that can compete with forces that are global in scale, involving the earth's tectonic plates, for 750 miles 1000's of feet deep of water were displaced vertically by as much as 30 feet? For heavens sake, it caused the world alter its natural wobble about its axis. It has permanently changed the length of a day. It caused waves to circumnavigate the globe several times. It caused islands to change their latitude and longitude. Are you seriously suggesting that a partial collapse of Cumbre Vieja would produce effects even remotely comparable to this (let alone dwarf the effects of the Indian Ocean tsunami?

Like you, I am not a geophysicist or geologist, but I am an engineer who has studied enough science and physics to form the conclusion that Simon Day's thesis of the effects of Cumbre Vieja is not believable, even in the slightest.

Also, I did not make unsourced claims. I immediately posted a link to the Tsunami Society, which dismisses Simon Day and the Discovery Channel.

but earthquake generated tsunami's are limited by the maximum vertical displacement of the earthquake.

I think that you understate the effect of earthquake-based tsunamis, much as Simon Day and those who believe with him. The potential devatsating effects of a tsunami are not determined just by the maximum vertical displacement. I saw that claim in the Discovery Channel special with Simon Day. They seem to follow the theory that the tsunami produced by an earthquake can only produce a wave as big as the vertical displacement of the water. This suggests to me a fundamental lack of understanding about tsunamis. The thing about tsunamis is the energy that they represent, not the height of the wave at any point. For instance, most tsunamis present themselves as a fairly small wave as the wave moves across the ocean, yet the power of that tsunami is not realized until it approaches shallower waters. To suggest that an earthquake generated by a sub-marine plate that rises from the ocean floor by, say, 30 feet completely ignores the depth of the ocean and the amount of water that is actually thrust upwards. To say that the wave is limited to 30 feet is to almost completely miss the most important factor in a tsunami... the potential energy that has been converted from plate stress to a lateral pressure wave of water where the amplitude of the wave is a fairly unimportant. For example, you could have a massive earthquake where the sea floor only raises a foot or two, but if happens at a depth of, say, 10,000 feet and the surface rises by a foot or two, then that should generate a much more powerful tsunami than one where the sea floor rises higher but at a shallower depth of water. The strength of the tsunami is proportional to the amount of water displaced, and that is a funtion of the depth of the sea where the sea floor rose. You also must factor in the length of the plate boundary where the earthquake occurred, in the case of the Indian Ocean, about 750 miles. If the Indian Ocean quake had been more of a point event, it would likely have been a much less devastating event. A point event, like a landslide-generated tsunami, produces more of a circularly radiating wave, which means that the energy dissipates in an inverse-square function. In other words, it cannot keep the same potential devastation regardless of the distance from the source because the area grows accordin g to the square of the radius. In the case of the Indian Ocean tsunami, the event was not a point event, it was a line event, and the resulting energy propagated mostly in an east-west fashion due to the north-south line of the tectonic plate boundary. This resulted in a largely linear propagation of the energy, rather than a radial propagation (as would happen with La Palma), and therefore the energy did not dissipate so much due to distance. It is a highly simplistic approach to say that because a landslide-based tsunami would generate a larger (probably much larger) surface wave at the source, that that compares with a much smaller wave at the source generated by a deep-ocean sea floor rise earthquake. Though it may be a larger wave at the surface, its not the height of the wave, its the energy behind the wave.

These principles of physics are largely ignored by the theories I have read. I have read Simon Day's paper that was the basis of the Discovery Channel. I found that he ignored these physical principles. He seemed to assume that a wave of one particular height could be compared with a much different wave of a lesser surface height (but much greater depth) as apples to apples. They are not.

Believe what you want. I can read both sides and decide to chose one over the other. By the way, I am quite capable of googling. And I did do a Google search prior to my post. Just because you disagree with me, you don't have to belittle my argument. Please state what YOU actually believe and discuss the details rather than just say that there are people who believe both ways.

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