Land of fire: scientists trek up violent volcanoes to answer some burning questions.
The volcano is Kilauea (KEE-lah-WAY-uh), and it's been erupting continuously for 22 years. As the scientists proceed on their dangerous hike, they spy a fiery prize: glowing streams of melted rock called lava are oozing down the volcano's slopes. The thick orange flows sizzle at a temperature of 1,150[degrees]C (2,102[degrees]F). The scientists can feel the heat from several feet away. "It's hotter than a burner on a stove," says Kauahikaua.
What exactly are the researchers doing in this scorching scene? By studying Kilauea's eruptions, these scientists hope to help predict when other volcanoes will erupt--a burning issue that could someday save lives.
Volcanoes are born when magma collects underneath Earth's surface. Most volcanoes form at the edges of plates--gigantic slabs of Earth that fit like a jigsaw puzzle. Sometimes these plates pull apart or ram together. This often causes red-hot magma to spill out onto the surface.
But Kilauea isn't your average volcano. Like every volcano that makes up the chain of Hawaiian islands, it formed over a pocket of heat deep inside Earth called a hot spot. This hot spot heated the rocks above it, causing magma to form. The magma was so hot it burned a hole through the middle of one of Earth's plates and spilled out onto the surface. As this melted rock cooled and hardened, it formed an island.
Over millions of years, the plate that the island sits on--known as the Pacific plate--has slowly moved northwest. As it moved, magma continued to burn holes through it, forming each of the chain's islands.
Although this much is known about the Hawaiian volcanoes, scientists still have more to learn. Kilauea is one of five volcanoes that make up Hawaii's Big Island. Of the five, it is the only volcano that is continuously erupting. Knowing exactly when the other four will erupt next remains a mystery. But by studying an active volcano like Kilauea, scientists have learned that there are signs a volcano gives before it erupts.
Searching for Signs
Several hours before an eruption, magma builds up in a chamber inside the volcano and makes the ground above puff up like a balloon. Although the swelling is too subtle for scientists like Kauahikaua to see, they can measure the slight changes with a tool called a tiltmeter. This device works like a carpenter's level to measure tilting in Earth's surface.
Scientists can also judge when an eruption is about to happen by studying the earthquakes that take place beforehand. As magma rises through the crust, it shifts rocks and triggers up to several hundred tiny earthquakes per day. The more often these earthquakes occur in a day, the more likely an eruption will occur.
Why is predicting eruptions such a hot topic? Hawaii's last killer eruption happened way back in 1790 and killed about 80 people, but more recent eruptions around the world have been much deadlier. For example, the 1985 eruption of Mount Ruiz in Columbia killed 23,000 people.
Getting a grasp on volcano behavior could prevent more deaths in the future. "The more we monitor eruptions now, the more warning we'll be able to give before the next big eruption happens," says Kauahikaua.
Words to Know
Volcano--a mountain formed by tara and ash
Lava--magma that has reached Earth's surface
Magma--liquid rock that is still underground
Plate--a giant stab of rock made of Earth's crust (outer layer) and mantle (middle layer)
Hot Spot--a pocket of heat deep inside Earth
HOW DO HAWAIIAN "HOT SPOT" VOLCANOES FROM?
1. A hot spot, shown here, is a pocket of heat deep inside Earth. It melts rocks above it to form magma.
2. The hot magma burns a hole through a rock slab called the Pacific plate. The magma then spills onto Earth's surface as lava.
3. The Pacific plate slowly drifts northwest. As it moves, magma formed by the hot spot continues to burn holes through it.
SCIENCE CONTENT STANDARDS
For Grades K-4
* Properties of earth's materials
* Science as a human endeavor
For Grades 5-8
* Structure of the earth
* Science as a human endeavor
INTEGRATE YOUR CURRICULUM
Language Arts--Reading Comprehension
Set a Purpose
To learn how volcanoes form, and how experts are learning to predict their dangerous eruptions.
* There are at least 1,500 active volcanoes around the world. The country with the most volcanoes is Indonesia. Most of the volcanoes in the United States can be found in Alaska. There are at least 262 volcanoes in this northern state.
* The largest volcano in the world is Mauna Loa, in Hawaii. It rises to 13,680 feet above sea level, or about 29,680 feet above the seafloor.
* What are some things you know about volcanoes? (Possible answers: They're very hot; they're like mountains; they spew out lava; they are dangerous.)
* Can you name any volcanoes in the United States? (Possible answers: Mount St. Helens in Washington; Mauna Loa in Hawaii.)
* Why is Hawaii a good place to study volcanoes? (Possible answer: The islands were formed by volcanoes; there are lots of volcanoes in Hawaii.)
* What are some ways scientists can tell that a volcano might erupt? (Possible answers: By using a tiltmeter; by measuring small earthquakes beforehand.)
* http://yahooligans.yahoo.com/content/science/brainpop/movie?id=volconoes Click on this link to watch a Brain Pop movie about volcanoes. The fun film explains how volcanoes form and erupt.
* Volcano: The Eruption and Healing of Mount St. Helens, by Patricia Lauber (Alladin, 1993), discusses the most dangerous volcano in North America. It's packed with great photos.
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|Title Annotation:||earth science|
|Date:||Sep 1, 2005|
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