Volcanoes Inside And Out

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j Millbrook Press /Minneapolis

Text copyright © 2006 by D. M. Souza Illustrations copyright © 2006 by Deborah and Allan Drew-Brook-Cormack The photograph on p. 48 appears courtesy of J.D. Griggs/U.S. Geological Survey. All rights reserved. International copyright secured. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means—electronic, mechanical, photocopying, recording, or otherwise—without the prior written permission of Millbrook Press, except for the inclusion of brief quotations in an acknowledged review. Millbrook Press A division of Lerner Publishing Group 241 First Avenue North Minneapolis, MN 55401 U.S.A. Website address: www.lernerbooks.com

Library of Congress Cataloging-in-Publication Data Souza, D. M. (Dorothy M.) Volcanoes inside and out / by D. M. Souza ; illustrations by Deborah Drew-BrookCormack and Allan Drew-Brook-Cormack. p. cm. — (On my own science) Includes bibliographical references. eISBN: 0-8225-6355-X 1. Volcanoes—Juvenile literature. 2. Plate tectonics—Juvenile literature. I. DrewBrook-Cormack, Deborah, ill. II. Drew-Brook-Cormack, Allan, ill. III. Title. IV. Series. QE521.3.S64 2006 551.21—dc22 2004027897 Manufactured in the United States of America 1 2 3 4 5 6 – DP – 11 10 09 08 07 06

for M.C. —DMS Success to all the future young volcanologists —Allan & Deborah

The mountain shakes and rumbles. Hot steam and burning rocks shoot high into the air.

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The sky turns fiery red, yellow, and orange. A volcano is waking from its sleep.

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People long ago believed volcanoes were the work of a fire god named Vulcan. They said that Vulcan had a workshop deep inside a mountain. There he made thunderbolts and weapons for other gods. The mountain spit out hot rocks and steam when Vulcan was busy. Since then, people have learned that volcanoes are not caused by Vulcan. They begin deep inside Earth.

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Inside Earth Far beneath our planet’s land and oceans is a thick layer of rock. This rocky layer is called Earth’s crust. It is many miles thick. The crust is not whole like a pie crust. It is broken into large parts called plates. The plates fit together like pieces of a giant jigsaw puzzle.

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The layer of Earth below the plates is also rocky and very hot. The fiery heat melts rocks into a thick liquid called magma. The magma bubbles and churns beneath the plates. The churning magma makes the plates move a few inches each year.

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Sometimes, plates bump into one another. The ground shakes and rumbles. We call it an earthquake. Other times, plates move apart. Then hot magma shoots through an opening called a vent. We say a volcano is erupting. Most volcanoes erupt along the edges of Earth’s plates. But once in a while, they erupt in the middle of plates.

Some volcanoes begin on land. Others begin under the ocean. They grow slowly. Most of them cannot be seen. But some underwater volcanoes grow to be giants. They rise up out of the water. These giant volcanoes form islands such as the Hawaiian Islands.

What makes magma move upward? Gases form in the fiery heat inside Earth. These gases move upward. They mix with magma and make it rise. Sometimes the gases make magma f low slowly from a vent. Other times, gases make magma suddenly erupt out of Earth. Gases in a bottle of soda do the same thing. Turn a bottle upside down. Gas bubbles slowly rise. Shake the bottle. Then open it carefully. The soda gases burst out of the opening.

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Once magma escapes from Earth, it is called lava. Hot lava burns everything in its path. It can destroy homes, cars, and entire towns or cities. Steam, rocks, and ash also burst out of the volcano. The rocks can be as small as baseballs or bigger than basketballs.

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After a volcano erupts, ash and rock pile up around the vent. They build until they look like the sides of a giant empty bowl. The bowl is called a crater. The stories you are about to read are about three different kinds of volcanoes. Each story is true.

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The Sleeping Giant Mount Saint Helens is a volcano in the State of Washington. In 1980, it had been quiet for more than one hundred years.

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Snow covered it in the winter. Flowers bloomed in the summer. People could see the mountain’s towering cone shape in the distance. They thought the mountain looked like a sleeping giant.

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The giant awoke one spring day. Earthquakes began shaking the snowy top of Mount Saint Helens. Magma rose inside the mountain. It made one side of the mountain swell. Then a powerful earthquake shook the ground around the mountain.

Hot lava, gases, and ash burst out of the swollen side. The mountain soon blew its top. Flowing lava quickly melted the snow. The water mixed with rocks and soil. This mudf low moved down the volcano faster than a speeding car on a freeway.

The volcano’s mudf low swept away trees, trucks, cabins, and animals. In some places, the mudf low was taller than a building with six f loors. Ash and steam rose above the explosion. They formed a cloud that hid the Sun. Winds carried the cloud miles away. One city became so dark that lights had to be turned on all day. Some people wore face masks when they went outside. They were afraid of choking on the dust and ash. At least 57 people lost their lives in the volcano’s eruption. Many birds and other animals died too.

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Mount Saint Helens is a kind of volcano called a composite volcano. Composite volcanoes are made of many layers of lava, rock, and ash. Most volcanoes around the world are composites.

Mount Fuji in Japan, Mount Vesuvius in Italy, and Mount Shasta in California are composite volcanoes. They all have steep sides. And they often blow apart without much warning.

A New Volcano One February day in 1943, a farmer was busy working in his field. He lived in a Mexican village called Paricutin. He and his family had been feeling strong earthquakes for weeks. On this day, the farmer heard a loud noise. The noise sounded like thunder. He looked up and saw a clear sky. No storm was in sight.

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Thunder rumbled again. Everything shook. Then the ground in front of the farmer swelled and cracked open. Dust and steam rose from the crack. A hissing noise grew louder and louder. The farmer became frightened. He moved a safe distance away. After he did, hot lava shot high into the air.

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The lava cooled as it fell to the ground. It hardened and broke into small pebbles called cinders. Trapped inside the cinders were bubbles of gas. The bubbles made the cinders look like glass. They piled up around the vent in the ground.

More lava burst from the volcano. The lava f lowed toward two villages. Soon the villages were buried. Dust and red-hot ash also burst from the volcano. The ash covered forests nearby.

The pile of cinders grew taller and taller. At the end of one year, the volcano was the size of a building with one hundred f loors. The volcano erupted for eight more years. But it did not grow much. Finally, one day it stopped hissing, rumbling, and spitting. The village named the volcano Paricutin. Paricutin is a kind of volcano called a cinder cone volcano. It is the first cinder cone volcano that anyone had ever seen being formed.

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Many other cinder cone volcanoes are in the western part of North America. All of them are in the shape of cones built with layers of cinders and ash. They are much smaller than composite volcanoes. Lassen Peak in California, Craters of the Moon in Idaho, and Sunset Crater in Arizona are all cinder cone volcanoes.

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Island of Fire On the night of March 24, 1984, small earthquakes shook the Big Island of Hawaii. Then a large earthquake struck early the next morning. People saw in the distance a bright red glow in the sky. It looked like the rising sun.

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The glow was coming from a wide mountain called Mauna Loa. The largest volcano on Earth had begun to erupt.

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Lava spilled out of the top of Mauna Loa. The hot liquid slowly f lowed down the volcano’s sides. It covered them with layer upon layer of lava. Fountains of lava also burst up from other openings around the mountain.

The hot liquid set plants blazing nearby. The burning plants filled the air with sparks and smoke. The lava moved over highways and toward the city of Hilo. Everyone waited and wondered. Would the city be buried under the liquid fire?

The lava f low slowed down before it reached Hilo. By April 14, the lava had stopped f lowing out of some parts of the volcano. Mauna Loa’s eruption ended the next day. Since then, the volcano has been quiet.

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Mauna Loa is a kind of volcano called a shield volcano. Shield volcanoes have wide sides. The sides are shaped like the rounded shields of warriors. All of the Hawaiian Islands formed from shield volcanoes. These volcanoes begin thousands of feet under the sea. They are the largest mountains on Earth. Iceland has other shield volcanoes that formed in the same way.

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Volcanic Activity About 50 to 70 volcanoes erupt around the world each year. Volcanoes that are erupting all the time are active volcanoes.

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Kilauea in Hawaii is an active volcano. Its last eruption began in 1983. Lava is still f lowing out of it. No one is sure when it will stop.

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Volcanoes that have been sleeping for many years are dormant volcanoes. But they could erupt again. Mount Etna in Italy and Popocatepetl in Mexico were dormant for many years. Then they exploded and became active once more.

A volcano that has not erupted for thousands of years is an extinct volcano. Mount Kenya in Africa is an extinct volcano. It is not expected to blow its top any time soon.

Changing the Earth Volcanoes can be terrifying. They have destroyed cities and killed people. But volcanoes can also be good for life on Earth. They have formed many islands, mountains, and parts of continents.

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Lava rocks help build roads. Beautiful stones from volcanoes are turned into jewelry. Pumice is a natural glass made from lava. It can grind and polish stones and metals. Pumice is also used in making hand soaps and household cleaners.

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People in some places turn heat from volcanoes into energy for electricity. The electricity lights homes and offices. It runs televisions and other machines. Rocks and ash from volcanoes. are good for farming soil. Vines, vegetables, and f lowers planted in this soil grow better than they do anywhere else.

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That is why people continue to live and work near dangerous volcanoes. But someday the volcano may awake again. Then everyone must be ready to run for safety.

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Studying Volcanoes Imagine being on an active volcano. Lava is bubbling out of several small holes. You walk closer to one of the holes. A blast of heat makes you turn away. The smell of rotten eggs fills the air. Suddenly, the ground shakes. You feel as if you are going to fall. This is a dangerous place. But some scientists actually work here. These men and women are called volcanologists. They study active volcanoes. Some of the volcanologists collect gas, rock, or ash samples from around vents. They wear helmets and masks for protection. Others dress in f iref ighters’ shirts and boots. They walk across lava and measure its temperature. Some scientists even stand near fountains of f ire during an eruption. They record what is happening. Other scientists set up special equipment and cameras. A few f ly over volcanoes in helicopters. They take pictures and report where lava is heading. Volcanologists try to understand everything about volcanoes. They want to make life safer for the people living and working nearby.

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Glossary Cinder cone volcano (SIHN-der COHN vahl-KAY-noh): A volcano built up almost completely by pebble-sized pieces of lava called cinders Composite volcano (cahm-PAH-ziht vahl-KAY-noh): A steep cone-shaped volcano built up by layers of lava, rocks, and ash Crater (CRAY-tehr): Bowl-shaped land around a volcano’s vent Dormant volcano (DOHR-mahnt vahl-KAY-noh): A volcano that is sleeping but may soon become active Erupt: (EE-ruhpt): To f low or burst out the way lava rushes from a volcano Extinct volcano (ek-STEENCT vahl-KAY-noh): A volcano that has not erupted for thousands of years Lava (LAH-vah): Melted rock from a volcano Magma (MAG-mah): Melted rock still inside Earth Plates (PLAYTS): Layers of rock beneath Earth’s land and sea that fit together like pieces of a jigsaw puzzle Shield volcano (SHEELD vahl-KAY-noh): A gently sloping volcano formed by f lowing lava Vent (VEHNT): an opening in Earth’s crust where melted rock escapes Volcanologists (Vuhl-keh-NAHL-oh-gihsts): scientists who study volcanoes

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Bibliography Colasurdo, Christine. “Nature Erupts in Spirit Lake’s Backcountry.” Pacific Discovery. 48 (1995): 8–16. Colasurdo, Christine. “Before the Mountain Blows.” Pacific Discovery. 49 (1996): 26–29. Decker, Robert W., and Barbara B. Decker. Mountains of Fire: The Nature of Volcanoes. New York: Cambridge University Press, 1991. Fisher, Richard V., Grant Heiken, and Jeffrey B. Hulen. Volcanoes: Crucibles of Change. Princeton, NJ: Princeton University Press, 1997. Francis, Peter. Volcanoes: A Planetary Perspective. New York: Oxford University Press, 1993. Pendick, Daniel. “What’s This Volcano Trying to Tell Us?” New Scientist. 161 (1999): 26–31. Robinson, Andrew. Earth Shock: Hurricanes, Volcanoes, Earthquakes, Tornadoes and Other Forces of Nature. New York: Thames and Hudson, 1993. Scarth, Alwyn. Volcanoes: An Introduction. College Station, TX: Texas A&M University Press, 1994. Scarth, Alwyn. Vulcan’s Fury: Man against the Volcano. New Haven, CT: Yale University Press, 1999. Sigurdsson, Haraldur, ed. Encyclopedia of Volcanoes. San Diego, CA: Academic Press, 2000. Thompson, Dick. Volcano Cowboys: The Rocky Evolution of a Dangerous Science. New York: St. Martin’s Press, 2000.