A volcano is a landform which serves as a vent that allows molten rock from the mantle, called magma, to reach the surface of the earth. Magma that flows to the Earth’s surface is called lava, and this could reach the surface through an effusive eruption or an explosive eruption.

How explosive a volcanic eruption is, depends on how much gas is trapped inside and the ease of flow of the magma. When huge amounts of carbon dioxide and water are combined with the magma, it behaves just like gas in fizzy drinks, which expands to form bubbles and then escapes. During a volcanic eruption, gas bubbles also form and greatly expand as magma rises to the surface of the Earth.

A volcano is considered as active if it releases gas and lava, and creates a seismic activity. On the other hand, it is classified as dormant if no volcanic eruption has occurred for a long period of time, although there is still a possibility that an eruption will take place in the future. When the dormancy of the volcano lasts for up to 10,000 years, it is considered as extinct.

The appearance and shape vary from one volcano to another. Some have shapes resembling a perfect cone, while others have deep depressions. The shape of the volcano tells a lot about the type of eruption, as well as its frequency and size.

There are different kinds of volcanoes, including shield volcanoes, cinder cones, lava domes, supervolcanoes, stratovolcanoes, subglacial volcanoes, and submarine volcanoes. Shield volcanoes are broad and are shaped like a shield, due to the slow and long flow of lava. On the other hand, lava domes are formed by lava that doesn’t flow too far. Cinder cones look like small hills that are shaped like a cone, while stratovolcanoes are tall, cone-shaped ones.

Other types of volcanoes include the subglacial volcanoes, which are located under glaciers; and the submarine volcanoes, which are situated on the floor of the ocean. Lastly, supervolcanoes refer to massive landforms that rarely explode.