There are four different types of volcanoes. A volcano is classified both by its formation and by its appearance. The different types of volcanoes also indicate the types of eruptions expected. The different types of volcanoes are: compounds (or stratovolcanoes), shields, ash cones and projection cones. Images of the four types of volcanoes can be seen all over the world, each type indicating the active underworld that we often think is static.
The layers, or strata, of rock and lava form the compounds or stratovolcanoes. These volcanoes have many shapes. A volcano composed like the mountain. Rainier looks like a helmet. The sides of this type of volcano are generally steep, with some reaching a pointed peak. Mountain. St. Helens, also in Washington, and Mt. Shasta in Northern California are the two compounds. In addition, the recognizable mount. Fuji in Japan is one of the largest composites in the world.
The compound volcano, when dormant, is generally a magnificent and impressive mountain. However, the eruptions are especially intense. As the magma rises to the point of eruption, it tends to become clogged due to its high viscosity. The pressure needed to force the magma out of the volcano is enormous and the result is an explosion of both rock and lava. It is quite dangerous to witness an eruption so close.
The shield volcanoes are also huge. However, they differ from stratovolcanoes because they are made up of many layers of flowing lava. Hot spots can occur away from the central ventilation of the volcano.
Shields burst frequently, but are not usually highly explosive. These are some of the best volcanic eruptions to observe from a relatively close distance, but still safe, as lava splashes are rare. Mauna Loa and Kilauea in Hawaii are both examples of a shielded volcano. Shields also form at the bottom of the ocean, gradually increasing in height through a constant flow of magma.
The ash cones are also relatively soft in eruption. They usually appear in the mountains with other types of volcanoes. A central ventilation forms a volcano formed by fragments of lava. The ash grows rapidly, but does not usually exceed 243.84 m (800 ft) in height. Ash is sometimes formed on the ground with no known history of volcanic activity. In 1934, Paricutín erupted from a field of Mexican corn and, in about five days, reached a height of 300 m.
Puu Oo, pronounced poo-oo, is a Hawaiian splashed cone that has produced a continuous flow of lava since 1983. Punctual eruptions have reached 1500 m. The lava flow tends to be low viscosity and moves easily along the cone to cover the surrounding area. The Hawaiian volcano caused the loss of a large number of useful land and roads due to the constant flow. Lava tends to drop from the initial eruption in splashed formations, making it dangerous to get too close. While restricting access to certain roads, Puu Oo added 544 acres of land to the main island of Hawaii.
Another classification of volcanoes is when geologists refer to a volcano as a complex. A complex volcano can be a combination of any of the above volcanoes, but is primarily classified by having at least two respirators, which often erupt very differently.