MAIN Science Earth Sciences Volcanoes

While the destructive force of volcanoes was made clear most famously in the US by the eruption of Mount St. Helens in 1980, volcanoes continue to make their presence felt worldwide.

Volcanoes are generally found where tectonic plates are pulled apart or come together, such as in Iceland and most famously in the Pacific Ring of Fire that encompasses the U.S. West Coast, Alaska and the Aleutians Island, and down along the whole of southern Asia.

Because the earth's crust is not uniformly thick, areas where the earth's shell stretches or thins result in volcanic eruptions such as in the East African Rift Valley, and the Wells Gray-Clearwater volcanic field in British Columbia.

"To make an omelet you have to break a few eggs" is an old adage that holds true for planet Earth with its yolk-like liquid core and thin, brittle shell or crust.

For eons, countless eruptions of hot volcanic lava at the surface have been responsible for than 80 percent of the earth's surface - forming the planet's mountains, plateaus and rich fertile farmlands.

Supervolcanoes

In the news in late 2008, Yellowstone National Park experienced unusually strong earthquakes that have worried American scientists. Lying beneath Yellowstone, and driving the world famous geyser Old Faithful, lies a churning mass of magma that some experts say will someday result in a supervolcano, spewing massive amounts of ash and dust enough to disrupt life around the planet.

Of the six known on Earth, three supervolcanoes can be found right within the US -- besides Yellowstone, there is one in Long Valley in central California, and another in northern New Mexico.

Elsewhere around the planet, the world's largest supervolcano lies on Lake Tabo in North Sumatra, Indonesia. Another supervolcano that last erupted in A.D. 181 is also still active on Lake Taupo, New Zealand.

Perhaps the most troubling of all is the Aira supervolcano in southern Japan, which has continued to rumble and cause the occasional earthquake located very near the city of Kagoshima (population 600,0000).

More about volcanoes around the Web:

Around the Web, take a closer look at volcanoes at top sites offering facts & information on the habits and history, where to find stunning photo galleries of recent volcanic eruptions, more on "submarine" volcanoes that happen under the sea, as well as kid-friendly resources and science projects for students & teachers ...

Volcanoes - Read the complete textbook online from the U.S. Geological Survey, with illustrated facts & information on volcano types and how they form, plus more on undersea volcanoes, plate tectonics and extraterrestrial volcanoes.

Volcanoes Exhibit - Here's a cool, interactive survey of volcano facts & information with detours to learning games & teacher lesson plans, volcano history, predictions & forecasting, related resources.

How Volcanoes Work - Find out with this extensive online encyclopedia featuring facts & information on volcano types, eruptions and famous volcanos, with interactive quizzes and printable crossword, related resources.

Volcano observatories online: