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While it may vary by volcano, the most abundant gas released during volcanic activity on average is water vapor. This is followed closely by carbon dioxide and sulfur oxide.


Volcanic eruptions can either be effusive or explosive. An effusive volcanic eruption occurs when the lava pours out onto the ground from the volcano's vent. When the molten rock or magma is thin and runny, gases can easily escape and the lava flows freely and travels f...


A volcanic eruption is caused by the injection of magma into a full magma chamber, the buoyancy of magma and the pressure exerted by the gases in the magma. The volcano simply acts as an opening through which magma and dissolved gases are discharged.


Volcanoes erupt due to pressure that the weight of the rocks puts on the magma and forces it to the surface out any available vent or exit provided to it. The magma is in a reservoir like area under the surface and the pressure from the rocks causes the less dense magma...


The first volcano erupted approximately 4.5 billion years ago. This is when the earth first came into existence, and long before the first humans walked the earth, according to Scholastic, Inc.


Volcanoes erupt to release pressure built up in the magma chamber by expelling the magma as lava. Along with lava, a volcanic eruption releases ash and greenhouse gases such as sulfur dioxide and carbon dioxide.


Some volcanoes erupt often and some are inactive for long periods of time. The amount of time between volcanic eruptions depends on the volcano itself, according to the Department of Geosciences at Oregon State University.


Volcanoes that have erupted within the last decade include Bulusan in the Phillippines and Copahue, which is near the border of Chile and Argentina. Some volcanoes, such as Kilauea in Hawaii and Mount Etna in Italy, have been erupting more or less continuously for decad...


A volcano that has recently erupted and may erupt again soon is categorized as an active volcano. Dormant and extinct are also categories of volcanoes.


Volcanic glass is typically called obsidian and is formed when viscous lava is rapidly cooled. This material contains between 65 to 80 percent silica and has a low water content. Obsidian is slightly more durable than window glass and possesses a glassy luster.