The world has thousands of volcanoes, many of them active, and any attempt at a list requires classification. Volcanoes can be grouped according to their type: stratovolcanoes and shield volcanoes, as is done by Oregon State University.Know More
Stratovolcanoes are sometimes known as composite cones, as they are built up by many layers of ash, pumice and other ejecta that has fallen near the base. These volcanoes tend to rise steeply, according to Wikipedia, and are characterized by their sudden, violently explosive eruptions that can sometimes blow the entire summit off the cone. Some active stratovolcanoes are Mt. Fuji in Japan and Tavurvur in Indonesia. Mt. Etna in Italy, is also a stratovolcano, but it is considered dormant.
Shield volcanoes tend to have lower profiles than stratovolcanoes as a result of having been built up almost entirely of liquid lava flows over the years. These flows can continue for a long time and gradually build up a low, massive mountain that resembles a shield resting against the ground. Notable shield volcanoes are Mauna Kea and Mauna Loa, both on the island of Hawaii, and Skjaldbriedour in Iceland. These volcanoes are active, as are 13 of the 21 known shield volcanoes of the Galapagos Island chain.Learn More
The three stages of a volcano are active, dormant and extinct. An active volcano is either erupting or showing signs that it is going to erupt, such as emitting gas. A dormant volcano is not active, but it could become active again, and an extinct volcano is unlikely to erupt again.Full Answer >
Quiet eruptions are volcanic eruptions that explode gently, with broad sheets of slowly flowing lava. Shield volcanoes, such as those in Hawaii, are commonly associated with quiet eruptions.Full Answer >
Volcanic craters and calderas differ mainly in the way they are formed. Craters tend to be more nearly circular than calderas, and they are often, though not always, smaller than calderas. Craters are the vents through which gas, magma and tephra are ejected, while calderas form as a result of local collapse of the surrounding rock.Full Answer >
There are three places a volcano can occur: at mid-ocean ridges, at subduction zones where a continental and ocean plate collide, and at a hot spot located in the middle of a plate. Mid-ocean ridges are caused by divergent tectonic plates and are the most volcanically active feature on earth.Full Answer >