Stages of Volcanic Activity
Volcanoes are classified as active or inactive. Inactive volcanoes are older and have usually erupted many times. A volcano is described as active if it is currently erupting or expected to erupt eventually.
A volcanic eruption occurs when lava, gasses, and other subterranean matter come out of the ground. The exact location of where they come out of is called a vent. A volcano usually has more than one vent. Eruptions can be violent or quiet. Some eruptions send lava high above the surface in spectacular fountain shapes. Violent eruptions such as these often include chunks of solid rock that were blown off the interior walls of the vent. Quiet eruptions consist of lava simply flowing out of vents. Both types of eruptions can also have gasses, such as sulfur and fluorine gas, coming out of vents.
Cooling and Inactive Stage
Even after a volcano stops erupting, gasses and vapors are still released. Some volcanoes, however, can end one period of eruptions and begin another after many years. Eventually, the volcano reaches the cooling stage. While the volcano cools, it reduces in size from water and weather erosion.
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Copyright 2007 Trey Tombari
Last updated March 15