Valcanoes

A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. When pressure builds up, eruptions occur.

In an eruption, gases and rock shoot up through the opening and spill over or fill the air with lava fragments. Eruptions can cause lava flows, hot ash flows, mudslides, avalanches, falling ash and floods.

The danger area around a volcano covers about a 20-mile radius.

Fresh volcanic ash, made of pulverized rock, can be harsh, acidic, gritty, glassy and smelly. The ash can cause damage to the lungs of older people, babies and people with respiratory problems.

Volcano eruptions have been known to knock down entire forests.

An erupting volcano can trigger tsunamis, flash floods, earthquakes, mudflows and rockfalls.

More than 80% of the earth's surface is volcanic in origin. The sea floor and some mountains were formed by countless volcanic eruptions. Gaseous emissions from volcano formed the earth's atmosphere.

                                                          

There are more than 500 active volcanoes in the world. More than half of these volcanoes are part of the "Ring of Fire," a region that encircles the Pacific Ocean.

Active volcanoes in the U.S. are found mainly in Hawaii, Alaska, California, Oregon and Washington, but the greatest chance of eruptions near areas where many people live is in Hawaii and Alaska.

Even though the volcanic eruption in Iceland was relatively small, the ash cloud that was produced disrupted European air travel for six days in April 2010. The eruption created the highest level of air travel disruption World War II.

Crater Lake in Oregon formed from a high volcano that lost its top after a series of tremendous explosions about 6,600 years ago.