A Volcano is any place on a planet where some material from the inside of the planet makes its way through to the planet's surface.

Magma is liquid rock inside a volcano.
Lava is liquid rock, or magma, that flows out of a volcano.

The name "volcano" came from the Roman god of fire, Vulcan.

Volcanoes vary a great deal in their destructive power. Some explode violently, destroying everything a mile away within minutes, while other volcanoes seep out lava so slowly that you can safely walk around them!

More than half of the Earth's volcanoes are located in the Ring of Fire, circling the Pacific Ocean. More than 80 percent of the Earth's surface, above and below sea level, is of volcanic origin. There are about 1500 active volcanoes on Earth. Indonesia has the most, followed by Japan and then The United States. Mauna Kea, in Hawaii, is the world's tallest volcano, over 30,000 feet high. The largest volcano in our solar system is Olympus Mons, on Mars. Most volcanoes are 10,000 to 100,000 years old.

There are five different types of volcanoes:
Composite or Stratovolcano, Cinder Cone, Shield, Caldera, and Fissure.

Did you know...

An active volcano is erupting or causing earthquakes, or releasing gases.

A dormant volcano is not showing any signs of activity, but has erupted within the last 10,000 years and may erupt again.

An extinct volcano has not erupted in 10,000 years.

Cinder Cone Volcanoes

Cinder cones are the simplest type of volcano. These volcanoes are made from erupting lava that breaks into small pieces as they blast into the air. When they erupt lava, it usually flows from a break in the side or base of the volcano, and not from the top.They are small, cone-shaped volcanoes, only about a mile across and up to about a thousand feet high. They have very steep sides and usually have a small crater on top.

Cinder cone volcanoes are often found on the sides of shield volcanoes. Cerro Nego in Nicaragua is the most active cinder cone. It last erupted in 1995. Mexico's Paricutin volcano, and Italy's Stromboli volcano are other examples.

 

Shield volcanoes have low slopes and are made from eruptions of flowing lava, usually from the sea floor. They are the largest volcanoes on Earth. This type of volcano can be hundreds of miles across with broad, gently sloping sides. They are island builders. They usually have large craters at the top. Many shield volcanoes erupt every few years!

The individual islands of Hawaii are large shield volcanoes. Mauna Loa, the largest of Hawaii's volcanoes, is also the largest single mountain in the world. It is about 60 miles long and 30 miles wide. Another shield volcano is Fernandia, on the Galapagos Islands. Olympus Mons, on planet Mars, is a shield volcano, and the largest known volcano in our solar system!

Calderas are circular depressions, found on the tops of many volcanoes. They can be difficult to recognize. The huge craters can be many tens of miles across. They form in gigantic eruptions that spew volcanic rocks out up to a thousand miles in all directions. The huge amount of magma that is spewed out leaves behind a large crater. That is how a caldera is formed.

Yellowstone Caldera, in our Yellowstone National Park in Wyoming, is an example of this type of volcano. It is so filled with lava and ash that you can hardly see the depression at all! Crater Lake Caldera in Oregon, United States is a caldera volcano and also Valles Caldera in New Mexico.

Fissure volcanoes are hard to recognize, too. There is no central crater at all! Instead, giant cracks open in the ground and spew out large amounts of lava that spread out and can cover almost everything in the area. After the lava cools, the surface is mostly flat. The cracks where the lava erupted are hidden, and that is why it is difficult to recognize this type of volcano.

Los Pilas volcano in Nicaragua is an example of this type of volcano. Laki is another fissure volcano, found in Iceland.