Special Reports

2000: Research at Mount St. Helens revolutionized predicting eruptions

In 1980, the science of predicting when volcanoes might erupt was a seat-of-the-pants kind of thing.

Don Swanson, one of the young hotshot volcanologists flown into Washington state by the U.S. Geological Survey, knew that the entire region around Mount St. Helens might be tilting as the mountain got ready to blow. To find out, he nailed yardsticks to stumps and docks along the waterline of Spirit Lake, reasoning that if the ground moved, the lake would tip.

"We turned the lake into the world's largest carpenter's level," Swanson explained. The instrument he created, he figured, was capable of giving readings accurate to one part in a million.

The tricky art of second-guessing volcanoes has changed significantly since then - in part because of research done at Mount St. Helens since the eruption.

Research on Mount St. Helens, aided by the new computer technology, satellite communication and high-tech instrumentation, has revolutionized the science of predicting when and where volcanoes will erupt.

It's still far from a sure thing, but thanks to techniques pioneered in Washington, thousands of lives have been saved in other eruptions around the world.

Swanson, now 61, and an affiliate professor at the University of Washington, is speaking tonight at the Mount St. Helens 20th Anniversary lecture series at Washington State University at Vancouver.

He'll be talking about the old days, when the impromptu encampment of geologists who converged on Vancouver in 1980 worked 16-hour days, catnapping in sleeping bags on the floor and feeding on junk food as they tried to predict when and how St. Helens would erupt.

That effort has evolved into the U.S. Geological Survey's sophisticated Cascades Volcano Observatory, still centered in Vancouver. The observatory is part research lab and part fire station. A rapid-response team of geologists stationed there can respond within 24 hours to threatening volcanic activity anywhere in the world.

Hazard prediction is the easiest type of research to get money for, because it has the most practical results in terms of effects on human life. Scientists at the observatory are constantly refining tools that detect the subtle movements in the Earth before volcanic events.

New tiltmeters, for example, are so sensitive they can detect changes in slope down to fractions of a single microradian. (One microradian can be envisioned by imagining a carpenter's level a half-mile long. Slipping a dime under one end of the level would change its tilt by approximately one microradian.)

New global positioning system (GPS) receivers use data transmitted by orbiting satellites to provide more precise readings of vertical and horizontal movements than ever before possible.

And new computer-assisted analyses of earthquakes provide instant computer images that track the underground movement of magma that precedes eruptions. Readings from these monitors can be telemetered to a central receiving site and automatically analyzed almost as quickly as they occur.

Like doctors on call, geologists at the Vancouver observatory take turns carrying a beeper programmed to go off when danger thresholds are reached, said Ed Klimasauskas, one of the geologists there.

A potential disaster that was avoided at Mount Pinatubo in the Philippines in 1991 was a sign of what's possible, Klimasauskas said. Geologists rushed into action weeks before the eruption, installed monitoring devices and advised an evacuation of 250,000 people. Thousands of lives were saved, Klimasauskas said.

But even with the new equipment, capable of such precise measurements, predicting what volcanoes might do is still far from an exact science. Geologists now realize it does not take an eruption to trigger volcanic disasters. Devastating mudflows called lahars can be set off by small avalanches or even heavy rain, in which case they occur suddenly - without warning.

St. Helens has a particular problem in that regard, Klimasauskas said. Geologists are worriedly watching as, winter by winter, snow and ice pack the bowl of Mount St. Helens' crater like a giant ice cream cone.

By last winter, 80 million cubic meters of snow and ice had built up inside the crater, a greater volume than all the material that swept down the north fork of the Toutle River in 1980.

"It's basically a lahar waiting to happen," Klimasauskas said.

Another worrisome possibility, he said, is that one of the high mountain lakes created in 1980 could break free of the unstable avalanche material containing it and flush down the Toutle River.

If that happens, he said, the speed and volume of material washed downstream would be so great that no measuring devices or warning systems would be of much use.

Originally published on May 15, 2000.