Just Something to Think About
The United States has 169 volcanoes, most of them in Alaska, the Aleutian Islands and in territories in the Pacific Ocean. Geologists warn that scenic Mount Rainier, near Seattle, is one of the most hazardous.
One of the planet’s largest volcanoes is the huge caldera that feeds the hot springs and geysers of Yellowstone. Although it has been restless in recent months with hundreds of small earthquakes, there is no sign of the kind of dramatic doming of the ground that indicates a major surge of magma and potential eruption. The caldera had a full-blown catastrophic explosion 640,000 years ago. The last significant eruption, known as the Pitchstone Plateau lava flow, took place 70,000 years ago. Jacob Lowenstern, the scientist in charge at the USGS Yellowstone Volcano Observatory, said tourists need not stay away for fear of what’s happening beneath the Park.
Volcanoes, though, can be mass killers. The relatively small eruption of Nevado del Ruiz in Colombia in 1985 created a mud flow that buried more than 23,000 people in the town of Armero. Hot gas and ash from Mount Pelée on the island of Martinique rolled down the slopes and incinerated 30,000 people in 1902.
Vesuvius, the volcano that buried the Roman city of Pompeii, is widely viewed as another disaster waiting to happen. It erupts about every 400 years and hasn’t had a large eruption since 1641. Hundreds of thousands of people live beneath it and could be hit with pyroclastic flows—extremely fast-moving, dense clouds of hot ash and rock that flow down a mountain.
“They’d have 15 minutes warning,” said volcanologist Michael Rampino of New York University. “It would destroy everything in its path. It’s like an ash hurricane that’s 800 degrees Celsius.”
Rampino said,”We live under the constant threat of some geological hazard. The more we all become technologically dependent upon others in other parts of the world, the more the problem shows up.”
“Volcanic risk is rising, not because we’re not doing our jobs, but because people are putting themselves nearer volcanoes, particularly with air travel,” said Marianne Guffanti, a geologist with the USGS.
Chris Waythomas, a USGS volcanologist in Alaska, said it is easy to detect when a volcano is active but hard to know what it will ultimately do, how long an eruption will continue and how big it will be.
There are surprises. Mount St. Helens, 1980: No one expected a major flank collapse to occur. That collapse depressurized the magma chamber below and caused the mountain to explode laterally.
Events related to the eruption of Eyjafjallajokull last May in Iceland demonstrated the inherent uncer-tainties of volcano science. Although volcanoes are far more predictable than earthquakes, they remain quirky, each one having its own personality. Scientists rely primarily on past performance to predict future activity for any given location. The Iceland volcano initially produced little ash, but a new vent opened beneath a glacier and the situation turned explosive. What precisely happened is being researched, but it appears that meltwater and magma produced steam quite suddenly and the volcano popped like a shaken soda bottle. The eruption was not large as volcanoes go, but the cloud that spread over Europe, making air travel difficult, shed light on the awkward overlay of human commerce and a hot, churning, unpredictable Earth. It raises the question of what governments can do to prepare for—and adapt to—wildcard geological events that not only affect airliners but can also alter the planet’s climate for years at a stretch.
The volcano with the difficult name of Eyjafjallajokull is not powerful enough to change the climate— it ejected material only as high as about 20,000 feet and would need to launch the ash to at least 33,000 feet to have global climatic effects, according to the National Oceanic and Atmospheric Administration.
No one can be entirely sure what will happen next in Iceland. Eyjafjallajokull could incite an eruption of its larger neighbor, Katla, which hasn’t erupted since 1918 and might be ready to rumble. In all three historically recorded eruptions of Eyjafjallajokull—in 920, 1612 and 1821—Katla erupted soon thereafter. Geologists drilling an explora-tory geothermal well into a volcano in Iceland got quite a surprise when the borehole filled with molten magma forcing the researchers to halt the drilling just last month.
As for the Yellowstone caldera, known as a supervolcano, no signs right now of any eruption, but if the ground begins to swell and dome, well, that would be a problem of enormous proportions.