pith helmet
Tales from the Field


Frightful fieldwork
Vulnerable to volcanoes
Hepatitis and blue berries
Antarctic anxiety
Human hazards


Krakatau (at right)
Image courtesy Volcano World, Univ. of North Dakota, (c) Robert W. Decker, used with permission.


Hot rocks + hot gas = dangerphoto of Krakatau
Volcanoes are a primordial force of nature, hewers of landscape, history, even climate. About 1900 years after the citizens of Pompeii were entombed by hot ash, the hazards of volcanoes have grown. Today, about 500 million people live dangerously close to deadly ash and lava.

Seattle, for example, lies within destructive range of Mount Rainier. But that's chump change compared to El Popocatepetl. The giant volcano is visible on the skyline of Mexico City -- the world's largest metropolis, and about 30 million people live nearby.

Plastercast of one fo the victims of Pompeii
Plaster cast of a victim in Pompeii
Courtesy Leo C. Curran.

Thus, while volcanologists are fascinated by hot lava -- and who wouldn't be? -- they are also obsessed with better volcano forecasts. Accurate forecasts of eruptions would allow prompt evacuation when necessary. Bogus warnings, on the other hand, cause havoc and make people less likely to heed the next warning. Today's eruption predictions rely on the earthquakes sparked by the rise of magma (molten, underground rock) inside a volcano. To improve those warnings, volcanologist Stanley Williams of Arizona State University studies gases -- rather than quakes -- released from rising magma. In volcanoes, as in soda bottles, gas is released when the pressure drops -- except that it's a bit more dramatic: Williams says the violent release of gas is what powers many explosive eruptions.

While you can safely measure earthquakes using seismometers that relay data via radio, measuring gas is tougher. One major gas, sulfur dioxide, can be measured with equipment designed to remotely monitor smokestack pollution. But measuring carbon dioxide, the predominant gas released in eruptions, might provide better clues to incipient eruptions, once someone figures out how to measure it. map of South America, showing where Galeras is located

In the danger zone
This long preamble explains the presence of Williams and a dozen colleagues on the high slopes of Galeras volcano in Colombia in 1993. The volcano seemed to be fading after several years of eruptions, says Williams, who has observed dozens of active volcanoes. "It felt safe. Though it was active, it had been quiet for almost six months."

Nevertheless, the scientists had taken the usual precautions -- radios, fireproof suits and helmets -- before climbing to retrieve gas samples from the cone. And that was just as well: "With a few seconds warning," Williams says, "it blew up, more powerful than anything before it."

Within a second, he says, six scientists were dead, and several were severely injured. "I was barely alive, had a hole knocked in my head, both legs broken," he recalls. Fortunately, a Colombian grad student named Marta Calvache hustled up to help the disoriented survivors, and she and others carried Williams in a blanket to safety.

The volcano was a hell on Earth, with hot, sharp flying rocks and gas up to 700 to 800 C -- hotter than molten lead. Those extreme conditions, Williams says, were "part of the reason that [the bodies of four scientists] were not found -- the rocks and gas just vaporized them."

Although Williams continues studying volcanoes, he's become more cautious. His wardrobe runs to the best helmets and fire-resistant clothing money can buy, and he's still trying to perfect remote sensors for carbon dioxide.

Leaving radio-transmitting carbon-dioxide sensors near a volcano seems a logical solution to the problem, he says, but the hot, acidic environment is almost as hard on equipment as it is on people. (See Why Files coverage of volcanoes, or an update on predictions at Mt. St. Helens.)

Dangerous natural forces may also be microscopic.


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