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How do Volcanoes Work?

Volcanoes are one of the most fascinating natural wonders on Earth. Their pure natural power and capability for mass destruction infect people across the world with a sense of awe. We all know that Volcanoes can be extremely devastating, but how and where do they form, and why do they explode? Most volcanoes that form on large bodies of land occur where two tectonic plates come together, and one of them is forced to subduct below the other one into the hot mantle. After this, the temperature and pressure increases, causing some of the rocks in the tectonic plate to melt and form magma. This magma in this area (called a subduction zone) forces its way to the surface, and forms volcanoes (Wheeling Jesuit University 2003). Alternatively, many volcanoes are also found in the oceans, at divergent plate boundaries. These spreading center volcanoes form at mid-oceanic ridges. At these divergent zones, magma pours out of the earth’s surface, becoming basaltic lava, which cools and forms new oceanic crust. This is vastly different than the explosiveness of volcanoes on land. Instead, it is a slow, gradual process. In general terminology, a volcano can be described as a place on a planet where material from the inside of the planet makes its way up through to the planet’s surface (Harris, 2004). Concerning volcanoes on land, our mantle is warmer than the surface. Rock inside our crust is then melted either by this heat from inside Earth’s surface, or by adding water to hot rock (which lowers the melting point). This hot melting rock (magma), combined with other gases, proceeds to explode through the earth’s crust, giving us an eruption. The actual volcano is the result of buildup of ash and lava (magma once it reaches Earth’s surface) flows from around the explosion area, or vent (Wood et al, 2004). Lava, pyroclasts, and gases (primarily water vapor, carbon dioxide, and sulfur dioxide) comprise the bulk of what comes out of volcanoes during their eruptions. Pyroclasts include dust, ash, bomb, pumice, cinder, and block (these are types of rock fragments that enter the Earth’s atmosphere during an eruption). The frequency of eruption determines the active status of a volcano. Extinct volcanoes are those that have not exploded since the beginning of recorded history. Dormant volcanoes are inactive, but not for a long enough period of time as to determine whether or not they will explode again. Intermittent volcanoes erupt fairly regularly. Active volcanoes erupt all the time. As I mentioned above, many volcanoes form in a subduction zone. Popocatepetl is one of these volcanoes. El Popo formed along a string of volcanoes occurring in a subduction zone known as the Ring of Fire. Follow the link below for more details.

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Ring of Fire
History of El Popo
Trouble Ahead for Popocatepetl?
Links to Other Volcano Sites
More Popocatepetl Pics!
Sources