Volcanoes can be extremely dangerous. The power a volcano has can be catastrophic! Earth alone has about 1,500 currently active volcanoes. The shape of a volcano may remain unchanged for centuries, and can change drastically in a matter of minutes. Most of the Earth’s volcanoes are seamounts; seamounts are volcanoes that are hidden beneath the surface of the ocean. Volcanoes are mainly vents and holes in the surface of the earth where heated materials escape from underground.

One type of volcano is a stratovolcano (also called compostite volcanoes). They have a very symmetrical cone shape. They can have slopes of up to 30 degrees at the summit. They’re mostly built up with layers of lava and pyroclastic. One example of a stratovolcano would be Mount Fuji in Japan. They may rise as much as 8,000 feet above their bases.

Shield volcanoes are built up of almost entirely lava flows. The flowing of lava pours out in many directions from the summit vent. This created a broad domical shape, which looks much like that of a warrior’s shield. A couple of the world’s largest volcanoes are shield volcanoes. In California, there are many shield volcanoes that have a diameter of around 3 or 4 miles with a height of 1,500 to 2,000 feet. Mauna Loa, located in Hawaii, is a shield volcano, and it’s the largest active volcano in the world.

Cinder cones are a pretty simple type of volcano. They are built from particles of lava that come from a single vent. As the lava is thrown into the air by pressure, it breaks into small fragments that turn into a solid and become cinders around the vent to make an oval cone. Almost all cinder cones have a bowl-shaped crater at the summit. They hardly ever rise more than a thousand feet in height. In western North America, there are a large variety of cinder volcanoes.

The Ring of Fire is a geographically active belt around the Pacific Ocean. Over 75 percent of the planet’s volcanoes are located there. Since they’re in the ocean, they are seamounts. The Ring of Fire is on the borders of the Pacific Plate, and is also around many other tectonic plates. Around the Ring of Fire, the Pacific Plate is colliding with and going underneath many other plates. This is called subduction. The energy created by the plates melts rock into magma. The magma then rises on the surface and forms into lava, which makes a volcano.

Close to ten percent of Earth’s volcanoes are located in the United States of America. There are many active volcanoes located in Alaska and Hawaii. Alaska has over 100 of them. Most of the volcanoes have been active within the last one and a half million years! They make up 80 percent of the volcanoes in the United States, and 8 percent of all the active above-water volcanoes on earth.

Kilauea has been Hawaii’s most active volcano during historical time. Since 1952, there have been 34 eruptions, and since January 1983 eruptive activity has been continuing along the east rift zone. The Hawaiian name “Kilauea” means “spewing” or “much spreading.” In recent times, eruptions have been continuous, with many of the lava flows reaching to the shore of the Pacific Ocean. Approximately 90 percent of the surface of Kilauea is lava flows less than 1,100 years old, and around 70 percent of the surface is under 600 years old.

Volcanoes are not only on the earth. They are located on other planets as well. One of these is Olympus Mons, a shield volcano, which is located on Mars. Rising 27 kilometers high, it’s by far the tallest volcano in the solar system. It’s around three times higher in elevation than Mount Everest, and Olympus Mons is Around 550 kilometers in width.

Mount Vesuvius is an active stratovolcano in Naples, Italy. It is very well known for destroying the cities of Pompeii and Herculaneum. Mount Vesuvius was formed by a collision of two tectonic plates. The mountain was created around 25,000 years ago, and has had many eruptions since then. One famous eruption was the Avellino eruption, which demolished many Bronze Age settlements.

Volcanoes remain a problem, and scientists are using new technology to predict when an eruption is about to occur. For all of the damage they cause, they’re still beautiful. Tourism is very popular when it comes to volcanoes. Ever wonder how many volcanoes are in the entire universe? The answer is too many to count!