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Pinatubo and Other Volcanoes With Attitude

12 minute read
Jeffrey Kluger

Any day now–at least according to government geologists–the little town of Orting, Washington, will cease to exist. Located in the thriving Seattle-Tacoma area, Orting, with its low crime rate and pleasant neighborhoods, has long been thought of as a delightful place to live. But it’s also an endangered place.

Like so many other towns in this part of the Pacific Northwest–including Microsoft’s hometown, Redmond–Orting was built in the shadow of Mount Rainier, and Mount Rainier has a nasty little secret. Beneath the 14,410-ft. mountain’s sugary caps and forested flanks lies a mammoth, smoldering pot of magma. Summoned up from the earth’s subterranean ovens perhaps 40 miles below, the molten rock simmers under the mountain at up to 3600[degrees]F. As the magma cooks the rocky innards of Mount Rainier, it slowly helps turn them into unstable clay. At the same time this internal furnace corrodes the mountain from the inside, rain and melting snow have been softening it up from the outside. The result, in the surprisingly colloquial argot of the geologist, is a mountain gone “rotten.” So rotten, in fact, that a mere seismic hiccup is all it would take to unleash an avalanche of mud on the homes below.

In 1980 another Northwestern peak–Mount St. Helens–went bad the same way, leading to a volcanic explosion that blew out the north face of the mountain, killing 60 people. While the more stable magma in Mount Rainier makes an eruption unlikely, the corroded state of the mountain could make a landslide even more devastating. Mount St. Helens, after all, had been baking for 100 years after its last blast; Mount Rainier has cooked for 500. “It’s only a matter of time,” says Dan Miller, a volcanologist with the U.S. Geological Survey (USGS), “before those towns near Rainier are buried.”

Washington State is not the only place where volcanoes loom. There are explosive mountains in every corner of the world. Late last week, Alaska’s Okmok volcano coughed a cloud of ash nearly a mile into the sky, perhaps presaging a period of increased volcanic activity. Near Mexico City, Popocatepetl, a 17,887-ft. volcanic peak, has begun to smoke and churn, threatening 500,000 people who live beneath it. In Italy five active volcanoes are being watched, the most menacing of which is the temperamental Vesuvius. In Japan 86 active volcanoes are packed onto an archipelago smaller than California. Other volcanoes sputter and steam in places as diverse as Ecuador and Alaska, Iceland and Indonesia. All told, there are more than 1,500 active volcanoes around the globe–550 or so on land and the rest underwater–that could put the lives of 500 million people at risk.

The threat volcanoes pose is nothing new, but popular appreciation of it is. The warning bell this time is being sounded not by scientists but by the entertainment industry. Two weeks ago, Universal Pictures released its heavily promoted volcano film, Dante’s Peak, and in April, 20th Century Fox will release its more prosaically named Volcano. abc television will air a documentary on the world’s most dangerous volcanoes next week, followed by a drama about an eruption at a West Coast ski resort.

While the stories the studios are telling are mostly make-believe, the danger is real. Increasingly, however, scientists can do something about it. They did so most famously in 1991, when they took the pulse of Mount Pinatubo in the Philippines, predicted it was about to erupt and persuaded officials to evacuate 35,000 people two days before it did. Researchers now have at their disposal an arsenal of newly developed volcanology hardware, ranging from satellites to acoustical sensors to highly sensitive gas sniffers. Whether the technology is up to the task of monitoring not just one peak but hundreds worldwide, though, is impossible to say, but the question is becoming pressing. “Someday,” says Robert Tilling, chief scientist of the USGS Volcano Hazards Program, “one of these mountains will erupt on a scale many orders of magnitude greater than mankind has ever seen.”

For all their fearsomeness volcanic mountains are relatively simple geologic structures–little more than lesions in the earthly dermis that suggest a fever condition far below. Volcanologically active areas generally lie atop clashing tectonic plates, where fractures five or six miles belowground create chambers into which magma rises and pools. The faster the plates collide, the more volcanic chambers are formed, which is why so many eruptions take place in the geologically active area of the Pacific known as the Ring of Fire.

Magma held in the chamber eventually makes its way toward the surface through channels in the overlying rock. As the ascending ooze climbs higher, the pressure on it is dramatically reduced, allowing gases trapped within to bubble out like carbonation in an opened bottle of soda. As this happens, the magma takes on a foamier consistency, increasing its speed and mobility. When this scalding froth rises high enough to make contact with subterranean water, the water flashes into steam, turning the whole hellish mix into a natural pressure cooker. Finally, the explosively pressurized magma blasts out of the earth in an eruption that can send rocks, ash and gases flying out at near supersonic speeds. “The driving force of an eruption is gas,” says Tilling. “Pressure builds up, some plug gives, and the whole thing goes.”

For the volcanologically untutored, there are worse ways to learn what a volcano looks like than to see Dante’s Peak. Though the story line is standard disaster-film fare, the science is generally sound. As the movie reveals, the first debris disgorged by a volcano is often a great gray mass of ash. The opaque cloud, made of pulverized rock and glass, falls like concrete snow on land and buildings miles away and may blot out the sun for days.

After the ash, some volcanoes produce what is known as a pyroclastic flow, a ground-hugging cloud of superheated gas and rock that forces a cushion of air down the mountainside at up to 100 m.p.h., incinerating anything in its path. Other mountains spew that signature substance of the volcano: lava. (On this point Dante’s Peak was wide of the scientific mark, concocting a fictitious mountain that produces both substances.) Lava moves at speeds ranging from less than 1 m.p.h. to 60 m.p.h.

For much of its history the U.S.–which before Mount St. Helens had largely been spared a major volcanic eruption–was complacent about this kind of devastation. After Mount St. Helens, all that changed. Hoping to improve prediction so that local populations could be evacuated before another mountain blew its top, the government set up volcano labs in Menlo Park, California; Vancouver, Washington; and Anchorage, Alaska, complementing one that already existed near the Kilauea volcano in Hawaii.

In addition, a rapid-response force known as the U.S. Volcano Disaster Assistance Program was established to act as a volcanic swat team, scrambling to the scene of an awakening mountain within days of the first sign of trouble. The group makes its services available not just in the U.S. but also overseas. It was this team that was largely behind the Mount Pinatubo success, packing hardware into suitcases and flying straight to the Philippines.

For any volcano researchers, predicting whether a smoking mountain is merely letting off steam or preparing to explode can be tricky–and often deadly. In 1993 volcanologist Stanley Williams of Arizona State University and six other scientists were working in a crater in the side of the Galeras volcano in Colombia when the mountain suddenly blew, killing all but Williams. USGS seismologist Bernard Chouet once trod so heedlessly over hot volcanic terrain that when he took off his shoes, his socks were smoking.

The stakes for the people living near the volcano can be higher still. In 1985 Colombian seismologists warned their government that the Mount Ruiz volcano was smoldering dangerously. Their data were too spotty to convince officials, however, and the government did nothing. One month later, the mountain erupted, claiming 23,000 lives.

Even when officials get it right, at least a little luck may often be involved. The first warning volcanologists got of increased seismic activity within Mount Pinatubo was not from a high-tech instrument but from a local nun who walked into the Philippine Institute of Volcanology and, begging the scientists’ pardon, reported that the mountain, clearly visible from her village, had just blown up. “The challenge is to call the eruption,” says USGS seismologist Dave Hill, “and that’s a fine line.”

One researcher who believes he may have learned to walk it is the USGS’s Chouet. Originally trained as a physicist, Chouet conducts his studies with a combination of ground-based instruments and high-orbit satellites. He first positions more than 40 seismic sensors around a part of a mountain where he suspects magma might be. Next he tunes the instruments to the military’s Global Positioning Satellite. As the sensors listen for subterranean rumbles, indicating the movement of materials within the mountain, the frequency of each rumble tells Chouet what those materials are. At the same time, the satellite pinpoints the position of the sensors to within an inch, allowing a computer to calculate the materials’ precise location. The system provides a picture of the mountain’s anatomy as revealing as any cat scan. “Volcanoes are singing when they’re pressurized,” Chouet says. “I can follow that process right up to the surface.”

Chouet is not the only researcher who’s using the orbital high ground to study the volcanic underground. In Alaska, USGS researchers have placed satellite receivers at different points on the sloping side of the Augustine volcano and tuned them also to the gps. Like any volcanic mountain, Augustine is swelling slightly as it fills with magma. The degree of this deformation–as calculated by the gps–can help determine the imminence of the eruption. Elsewhere, scientists are leasing time on European or Japanese satellites to take photos of volcanic peaks as they undergo a seismic event like an earthquake. Imaging hardware then measures the precise distance between the satellites and any point on the mountain. If that distance changes as the spacecraft make repeated passes over a peak, scientists can determine how much the ground moved as a result of the event and, by inference, how stable it is.

But cracking volcanic secrets doesn’t always require such sophisticated instruments. Increasingly, researchers have come to appreciate that volcanoes, like living organisms, have their own internal metabolisms, and like any metabolic system, they give off telltale waste products–particularly gases. Williams is developing a new way to read those gases and predict just when a mountain will probably detonate.

As magma rises in a volcano, light molecules like carbon dioxide bleed off more than heavier gases like sulfur dioxide. The higher the CO[2] levels, the likelier an eruption. If magma gets stuck in the gullet of the mountain, SO[2] predominates. The more SO[2], the more stagnant the magma and the less probable an eruption. The problem is that taking accurate measurements may require climbing almost directly into a volcano–a decidedly dangerous proposition.

To reduce the risk, Williams is testing a remote gas sensor that can read a volcano’s emissions from a plane flying nearby or even a car driving past at a distance of as much as 20 miles. The instrument works by detecting changes in the infrared energy caused by different gases in the volcanic plume. Says Williams: “Volcanoes give gaseous signals of approaching eruptions. This gives us the lead time we need to get people educated and not terrorized.”

Even if new gas-sniffing and satellite equipment succeeds in keeping people on the ground safe from volcanoes, people in the skies could still be at risk. For them the danger comes from volcanic ash, which can choke the engines of passenger jets. Since the 1960s there have been 85 such midair encounters, and while none have led to a fatal crash, some have come close.

To combat the problem, the USGS is deploying detectors around volcanoes so that air-traffic controllers can be alerted when an ash cloud belches forth. While this could go a long way toward making the skies safer, the business of setting up the instruments is going slowly. Currently, the faa, which funds the project, is devoting only $2 million a year to it, barely enough to equip two volcanoes. At that rate, it would take 275 years before all the world’s active peaks were covered.

This dilemma is typical of volcanology as a whole: more and more, researchers are realizing that the degree of protection their science can offer will be directly linked to the amount of money it receives. The USGS volcano program has been getting by on what in Big Science is a starvation ration: $17 million annually. Next year even that will be slashed by $2 million. The USGS’s volcano swat team carries out its volcanic smoke jumping on a budget of just $750,000 a year.

Nobody pretends this is enough to sustain global volcano work, and while a few countries have monitoring programs of their own, many of the Third World nations that are in the greatest danger are the least economically equipped to address it. The U.S. thus finds itself in a familiar leadership role at a time when its own federal budget is under growing pressure. At the USGS researchers can only hope that the funds for their work don’t disappear before they have a chance to warn the world of the next volcanic disaster.

“Volcanoes are enthralling,” says Smithsonian Institution volcanologist Richard Fiske. “You can’t stop them. You can’t control them. All society can do is learn to coexist with them.”

–Reported by Dan Cray/Los Angeles and Dick Thompson/Menlo Park, with other bureaus

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Write to Jeffrey Kluger at jeffrey.kluger@time.com