What is Volcanoes? What are the types of Volcanoes?

Volcanoes form when magma a mixture of hot gas, ash, and melted rock-erupts from a crack in the Earth’s surface. The melted rock, called lava, flows out and hardens. As layers of lava build up, the volcano gets bigger. A volcano can be active, dormant, or extinct. Volcanoes can and have existed on other worlds as well: although volcanoes on the moon and Mars have long been dormant, volcanoes are still very active on Jupiter’s moon Io. Researchers are currently striving to find ways to predict when volcanic eruptions might happen on Earth by analyzing clues such as crystals and gases linked with volcanoes.


Stratovolcanoes are tall and cone-shaped, with steep sides. They are made up of lots of layers of lava and ash that have cooled and hardened. Their eruptions can be very powerful and dangerous.

Stratovolcanoes are also called composite volcanoes because they are built of layers of alternating lava flow, ash and blocks of unmelted stone, according to the U.S. Geological Survey. They are larger than cinder cones, rising up to 8,000 feet (2,438 meters). Stratovolcanoes result from a conduit system of vents leading from a magma reservoir beneath the surface. When dormant, they typically have steep concave sides that sweep together at the top around a relatively small crater.


Shield volcanoes have gently sloping side and are formed from thin, runny lava. Their eruptions are less explosive and much less dangerous than other volcanoes. These gentle eruptions can continue for years. Eruptions of these volcanoes are not generally explosive, but are more like liquid overflowing around the edges of a container. The world’s largest volcano, Mauna Loa in Hawaii, is a shield volcano, according to the U.S. Geological Survey. Mauna Loa is about 55,770 feet (17,000 meters) from its base beneath the ocean to the summit, which is 13,681 feet (4,170 meters) above sea level. It is also one of the Earth’s most active volcanoes and is carefully monitored. The most recent eruption was in 1984.

Cinder Cone

Cinder cone volcanoes are the smallest and most common type of volcano. They are cone-shaped with steep sides. Their eruptions are usually not too violent. They may occur as single volcanoes or as secondary volcanoes known as “parasitic cones” on the sides of stratovolcanoes or shield volcanoes. Airborne fragments of lava, called tephra, are ejected from a single vent. The lava cools rapidly and fall as cinders that build up around the vent, forming a crater at the summit, according to the U.S. Geological Survey.


Calderas are large, circular hollows, almost like a bowl. They form when a massive eruption forces most of the magma out of the chamber under the volcano, causing it to collapse. Craters are usually more circular than calderas. (Calderas may have parts of their sides missing because land collapses unevenly.) Craters are also usually much smaller than calderas, only extending to a maximum of one kilometer (less than a mile) in diameter. 


Picture Credit : Google