Volcanoes Kevan and Alexiz Per.1 5/16/12

Some facts about Volcanoes A volcanic eruption can be very dangerous for people living near a volcano. Volcanic flow can reach to temperatures of 2,000 degrees Fahrenheit or more and they could end up being deadly. The flow can get rid of mountains and valleys and bury towns. Ash and toxic gases can cause lung damage and other problems, especially for babies and the elderly. It has been estimated that 260,000 people have died in the past 300 years from volcanic eruptions and their aftermath. Volcanoes mostly exist along the edges between tectonic plates, massive rock slabs that make up Earth's surface. About 90 percent of all volcanoes exist within the edges of the Pacific Ocean or otherwise called “The Ring of Fire”. About 1,900 volcanoes on Earth are considered active, which means they are likely to explode again. Many other volcanoes are dormant, which means no current signs of exploding but likely to become active at some point in the future. Other volcanoes are considered extinct.

Types of Volcanoes There are four main types of volcanoes and they are composite, shield, cinder, and spatter volcanoes. The first one that I am going to mention is composite. They are formed by altering layers of lava and rock fragments and they are also know as strato-volcanoes.

Composite Volcanoes

Shield Volcanoes Shield Volcanoes are some of the largest volcanoes . They are made up of many layers of lava that flows throughout the volcano. This lava flows out of a middle vent or different vents that are grouped together. For the most part, they occur along the mid-oceanic ridge, where sea-floor spreading is in progress and along subduction related volcanic arcs. Their eruptions are characterized by low-explosive lava-fountaining that forms cinder cones and spatter cones at the vent.

Examples

Cinder cones Cinder cones are probably the most common volcanoes and also are steep sided Cinders are melted volcanic rock and they are ejected from a single vent and accumulate around the vent They are formed by strombolian eruptions and grow rapidly The longer the eruption of a cone, the higher the cone is.

Some examples of cinder cones

Splatter volcanoes Splatter volcanoes are formed by lava ejected from a vent Expanding gases from the lava form a heap around the vent They are normal volcanoes that have high fluid magma which usually come from the Hawaiian islands.

Examples