Volcanoes and Earthquake Assignment Example | Topics and Well Written Essays - 1500 words

Volcanoes and Earthquake - Assignment Example Lava with low viscosity forms a shield mountain, which is low-lying because it flows over a long distance. On the other hand, the lava with high viscosity forms a dome-shaped mountain because it flows over a short distance before solidification (Gill, 2009). High silica content leads to the formation of a magma and lava that is more viscous than when the silica content is low. The viscosity is high because of the strong bonds between silica and oxygen. Intrusive igneous rocks refer to the igneous rocks that form when magma crystallizes within the Earth’s crust. Granite is the common example of intrusive igneous rocks. Extrusive igneous rocks refer to the igneous rocks that form when magma crystallizes on the Earth’s surface (Gill, 2009). Basalt is the common example of extrusive igneous rocks. On the other hand, the lava with high viscosity forms a dome-shaped mountain because it flows over a short distance before solidification (Gill, 2009). A pyroclastic flow refers t o a fast-moving mass of hot rocks and gases. It is evident that a pyroclastic flow is explosive because of the fast-moving gases. The volcanic eruption from St. Augustine volcano is an example of the volcano that produced a pyroclastic flow. A lava flow refers the movement molten rock from a volcanic mountain at a slow speed due to the absence of hot gases (Gill, 2009). It is evident that a volcanic flow is effusive because it does not involve hot gases. The volcanic eruption from Mauna Loa volcano is an example of the volcano that produced a lava flow. A supervolcano refers to a volcano that can produce an eruption with a large volume of about 1000 km3. An example of a supervolcano is Yellowstone.  Intrusive igneous rocks from within the vents before the magma moves to the Earth’s surface.