A volcano is little more than a crack, rupture or opening in the Earth’s crust. The lava that protrudes from the volcano is hot, molten rock, ash, and gases that escape from below the surface of the Earth. There are features of volcanoes that form over time by the extrusions of rocks that form when tectonic plates converge.
Hotspots are places where convergent tectonic plates come together, but volcanoes are not usually located where these plates slide against one another. Rather, hotspots are typically located where there is a stretching and thinning of the Earth’s surface and where hot material is heated until it reaches the crust. These hotspots cause plumes. New volcanoes are formed as plates shift over hotspots. The Hawaiian Islands are thought to be formed by hotspots.
Lava is defined by what types of materials it is composed of. There are generally four types of lava: felsic, intermediate, mafic, or ultramafic. The amount of magma contained in the lava is the largest factor in determining which specific type of lava is present. The lava texture will differ depending on both its composition and its method of flow. A slower flowing lava will be thicker while a faster moving lava is generally thinner.
3. Space volcanoes
Cryovolcanoes (or ice volcanoes), can be found on some moons of the moons of Jupiter, Saturn, and Neptune. The Earth’s Moon has no large volcanoes and no current volcanic activity
4. Shield volcanoes
Shield volcanoes have shield-like profiles (thus their names). These volcanoes are formed by the eruption of lavas that can flow a great distance from a vent (or crack in the Earth’s crust). Shield volcanoes do not generally have the big dramatic explosion that some of the more recognizable volcanoes have. The volcanoes found on the Hawaiian islands (not the islands themselves) are a series of shield volcanoes.
5. Lava domes
Lava domes are created by the gradual formation of a volcano from the build up of highly active lava flow. Just like Mount Saint Helens, lava dome volcanoes are sometimes formed in the craters caused by previous volcanic eruptions.
A Supervolcano is a very large volcano that has the potential of producing large scale devastation. These are the types of volcanoes that come to mind when most people think of what a volcano is. Huge volumes of sulfur and ash can come from these volcanoes. The impact on the environment can be so big that global temperatures are changed as a result of the eruptions.
7. Submarine volcanoes
You guessed it, submarine volcanoes are found on the floor of the ocean. Most submarine volcanoes lay so deep in the water that the water pressure prevents them from exploding any sort of debris or gases. These volcanoes are typically thinner and taller than the ones that are found on land due to the effects of buoyancy.
8. Subglacial volcanoes
These volcanoes form underneath the ice. Most of the best examples of subglacial volcanoes can be found in Iceland.
9. Dormant and active
Most volcanoes are classified by their frequency of eruption. A volcano that has frequent eruptions is classified as an active volcano while a volcano that may have been active at one time but has not had activity for a while is called a dormant volcano. Volcanoes that have never erupted are called extinct volcanoes.
10. The history of the volcano
The term volcano is said to have originated in Italy and the word volcano comes from the Roman god of fire, Vulcan. The Roman name for island is Vulcano. Volcanoes have a colorful history as many ancient accounts attributed volcanic eruptions to supernatural causes.
Learn more with these Volcanoes websites.