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Watching Volcanoes

Ancient man thought eruptions were caused by gods; today, scientists are learning to predict them

When Dan Dzurisin was eight years old, he dreamed of working for the United States space program. Today, instead of looking to the heavens, he spends his days looking beneath his feet. He's a geologist studying the hundreds of volcanoes that dot the globe.

A volcano is formed when liquid rock inside the earth boils up through a crack or hole in the earth's crust.

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Dr. Dzurisin says switching from space to volcanoes wasn't such a big leap.

"It was a natural progression," he says at the Cascades Volcano Observatory in Vancouver, Wash., where he works for the US Geological Survey. He wanted to be in the space program "because I thought the planets must be neat places to observe and study."

He earned a doctorate by studying photos of Mars and Mercury taken by unmanned spacecraft. He was trying to figure out what forces - including volcanic ones - had shaped the surfaces of the planets. Later, while living in Hawaii, he fell in love with the spectacular lava flows on the island of Hawaii. (When molten rock is underground, it's called magma. When it comes to the surface, it's lava.)

"I decided I wanted to work on volcanoes, but the most exciting ones were on Earth," he concluded.

Volcanoes take their name from Vulcan, an ancient Roman god who supposedly hammered out thunderbolts and armor for Hercules in his underground blacksmith shop. You could tell he was working by all the smoke and fire that rose from the shaky Mediterranean island of Volcano off the Italian coast.

Having a blast in 1980

The observatory where Dzurisin is based sits in a quiet neighborhood of family homes near the Washington-Oregon border. There, he monitors instruments that listen to one of the world's most famous volcanoes: Mt. St. Helens.

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The mountain is 45 miles away. It's quiet now, but 17 years ago a huge eruption occurred. Pressure that had built underneath its snow-capped summit exploded into the air on May 18, 1980. It set off the largest landslide in recorded history and blew out one side of the mountain.

The blast sent hot material flying sideways at 600 m.p.h. and a column of ash and gas 15 miles into the atmosphere. More than 500 million tons of ash were carried eastward across the United States. The cloud was so thick that it darkened the sky in Spokane, Wash., 250 miles away.

Dzurisin was off studying volcanoes in Hawaii at the time, but returned to Washington the day after Mt. St. Helens had made world headlines.

He'd missed the first eruption, but the mountain wasn't done yet. It erupted again a week later. Over the next year and a half, five smaller eruptions occurred. Then it quieted down.

Volcanologists keep a close eye on Mt. St. Helens. They check readings and measurements from instruments at the crater, including a seismometer atop the lava dome that plugs the central vent. Seismometers (size-MOM-uh-ters) measure earthquakes.

Mt. St. Helens is considered an active volcano, though there has been no lava flow since 1986. The mountain had a major eruption in 1857, and volcanoes in the Cascade Range average about two eruptions per century. There are 15 volcanoes in the Cascade Range, a chain of mountains that run from northern California to western Canada. It includes Mt. Ranier, which is easily seen from the cities of Seattle and Tacoma, Wash.

Reducing the risk of volcanoes

"The reason we study volcanoes is to try to reduce the risks," Dzurisin says. "The dangers can be lessened by modern science because, in almost all cases, volcanoes do give warning before they erupt."

In the case of Mt. St. Helens, a series of small earthquakes raised concern two months before the 1980 eruption. Other signs that something big was about to happen piled up. Instruments detected numerous quakes, cracks began to appear on the crater, and the north flank of the mountain started to bulge. People were ordered to evacuate, but not everyone did. Fifty-seven people died in the blast that destroyed 150,000 square acres of forest and knocked over large trees as if they were toothpicks.

Despite the devastation, life is returning here. Plants and animals are rebuilding the habitat. Some burrowing animals even survived the blast. But it will be many years before tall evergreens again cloak the rolling terrain.

Volcanoes occur at thin spots in the earth's crust. These spots are often along the joints of the continent-sized plates that make up the earth's surface. This is the case in America's Pacific Northwest.

Dzurisin and his fellow scientists studying the globe's 1,500 volcanoes spend a lot of time sharing information. They write reports and give presentations. They also may quickly fly to any volcano that's rumbling to life in order to study it. That way they can learn more about these geologic wonders and be better prepared to respond to them.

Make Your Own Volcano

It's a very safe volcano, of course, but it does 'erupt' nicely

You will need:


baking soda

measuring spoons

two-cup measure

red food coloring

an empty frozen-juice can

a sandbox

Build a volcano-shaped mound of sand in a sandbox. Dig a hole at the top and put the empty juice can in it with the open end straight up. Put sand around the can so that the top of it is flush with the top of your volcano.

Put a tablespoon of baking soda in the can. Pour one cup of vinegar into a two-cup measure, and add about 20 drops of red food coloring.

Ready? Pour the colored vinegar into the juice can! The vinegar, which is acidic, will react with the baking soda (which is basic) to form bubbles of carbon-dioxide gas. (Carbon dioxide gives soda pop its fizz.) The bubbly red flow simulates the lava of a volcanic eruption.

Variations: Some volcano "recipes" call for a 16-oz. soda bottle instead of a juice can (pour in half the vinegar at a time). A squirt of dishwashing liquid or a tablespoon of flour in the juice can/soda bottle adds to the foaming effect.

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