Volcanoes

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A volcano erupts when the pressure of a subterranean pool of magma becomes great enough to crack the earth's crust. Whether the eruption results in a violent explosion or a slow seepage depends on several different factors, according to How Stuff Works.

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  • What is a composite cone volcano?

    Q: What is a composite cone volcano?

    A: A composite cone volcano, or a stratovolcano, is built by multiple eruptions from surrounding volcanoes. They are formed over hundreds of thousands of years and have their entire structure build by magma flowing from geographically close volcanoes.
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  • What is the difference between magma and lava?

    Q: What is the difference between magma and lava?

    A: Magma and lava are the same substance in two different forms. Magma is molten rock that is found beneath the earth's crust, while lava is what magma becomes once it reaches the surface and erupts from a volcano or crack in the earth.
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  • What is an extinct volcano?

    Q: What is an extinct volcano?

    A: An extinct volcano is one that has not erupted in at least 10,000 years and is not expected to erupt in the future, according to Oregon State University. There can be confusion between dormant and extinct volcanoes, but the difference between the two is that a dormant volcano may erupt even if it is in the distant future.
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  • How are inselbergs formed?

    Q: How are inselbergs formed?

    A: Inselbergs, or isolated rock hills or mountains, are formed by erosion and long-term weathering. A type of disintegration landform, inselbergs are steep sided and rise abruptly from a gently sloping terrain or level surrounding plain. Their formation may be initiated by a volcanic process that causes a body of relatively erosion-resistant hard rock inside a body of softer rock to rise, which eventually erodes to expose the inner hard-rock portion.
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  • Where is Mount Kilimanjaro located?

    Q: Where is Mount Kilimanjaro located?

    A: Mount Kilimanjaro is located in Tanzania. It is a dormant volcano comprising three volcanic cones, and is the highest peak in Africa.
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  • What are active and inactive volcanoes?

    Q: What are active and inactive volcanoes?

    A: Active volcanoes are those that have erupted recently or regularly erupt, and inactive volcanoes are those that have not erupted for a long time. The exact time distinction between active and inactive volcanoes differs between experts.
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  • When did Mount Rainier last erupt?

    Q: When did Mount Rainier last erupt?

    A: Washington state's Mount Rainier last erupted between 1894 and 1895, according to Geology.com. Residents of nearby cities heard explosions coming from the volcano's summit. Geologists believe that Mt. Rainier is due to erupt again in the near future.
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  • Why are there volcanoes?

    Q: Why are there volcanoes?

    A: Volcanic vents allow the Earth to release built up gases from the heat and pressure emanating from its core. Magma rises towards the surface, and as the pressure builds the magma seeks outlets through which to flow. The higher the pressure build-up, the greater the volcanic explosion.
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  • Are volcanoes mountains?

    Q: Are volcanoes mountains?

    A: While many volcanoes are mountains, it is possible for a volcano to erupt from a vent in any type of land form. Over time, volcanoes become mountains by depositing their discharge around them in ever-increasing layers. Not all mountains are volcanoes.
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  • What gases are produced by volcanic eruptions?

    Q: What gases are produced by volcanic eruptions?

    A: Volcanic eruptions mainly produce steam (H2 0 ), sulfur dioxide (SO 2 ) and carbon dioxide (CO 2 ). They do release other gases in lesser amounts, such as carbon monoxide (CO), helium (He), hydrogen (H 2 ), hydrogen chloride (HCL), hydrogen fluoride (HF) and hydrogen sulfide (H 2 S).
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  • What is an ash cloud?

    Q: What is an ash cloud?

    A: An ash cloud is a large cloud of smoke and debris that forms over a volcano after it erupts. Ash clouds consist of several elements, including ash, gases, dust, steam, rock fragments and other materials that come from inside the volcano and combine in the air above the crater.
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  • How many super volcanoes are there in the world?

    Q: How many super volcanoes are there in the world?

    A: The Earth has approximately 20 known supervolcanoes, according to James Morgan, who write for the BBC News. What constitutes a "supervolcano" is not clearly defined, so the term is avoided in the literature, but it is often used in reference to two distinct phenomena.
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  • What are the different parts of a volcano?

    Q: What are the different parts of a volcano?

    A: The main parts of a volcano include the summit crater, the magma chamber, the central vent and the edifice. While volcanoes vary considerably in terms of size and shape, most land volcanoes have structural similarities.
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  • What country has the most active volcanoes?

    Q: What country has the most active volcanoes?

    A: Indonesia has 147 volcanoes, 76 of which are still active making it the world's most active volcano country. The country consists of a chain of more than 13,000 islands that are spread out over an area similar in size to the continental United States.
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  • How tall is Mount Vesuvius?

    Q: How tall is Mount Vesuvius?

    A: Mount Vesuvius is a volcano that is roughly 4,300 feet tall, according to About.com's Ancient/Classical History expert. It is located in Italy, near the Bay of Naples.
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  • What do volcanologists do?

    Q: What do volcanologists do?

    A: Volcanologists study the processes of volcano formation and their eruptive activity. In addition to studying current volcanic activity, they also study the eruptions of volcanoes throughout history.
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  • What is the oldest volcano in the world?

    Q: What is the oldest volcano in the world?

    A: Mt. Etna is considered the oldest volcano in the world. Its first recorded eruption took place around 1500 B.C.E. Since that date, the volcano is believed to have erupted an additional 190 times.
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  • What damage do volcanoes cause?

    Q: What damage do volcanoes cause?

    A: Volcanoes cause physical damage to structures and buildings, wildlife, local vegetation and the atmosphere, as well as posing health risks. Residences within the vicinity of a volcanic eruption often receive timely notice before an eruption occurs. This reduces the likelihood of danger to humans.
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  • What is a lateral blast?

    Q: What is a lateral blast?

    A: A lateral blast, also known as a lateral eruption, is a volcanic eruption that occurs out of the side of a volcano instead of at its summit. An example of a lateral blast is the 1980 eruption of Mount St. Helens.
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  • What is the most destructive volcano in the world?

    Q: What is the most destructive volcano in the world?

    A: To humans, the most destructive volcano in the world is Mount Tambora in Indonesia. This volcano created the most powerful eruption in known history and killed 100,000 people along the way. Its eruption was 100 times more powerful than Vesuvius.
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  • What conditions make for a violent volcanic eruption?

    Q: What conditions make for a violent volcanic eruption?

    A: According to the Oregon State University Department of Geosciences, a volcanic eruption may become violent if pressure builds up inside the volcano for any reason. An explosive eruption is much more dangerous than a steady flow of magma and can spread ash and pyroclastic material over a wide area. The eruption of Mount Saint Helens in 1980 was a textbook example of a violent, explosive volcanic eruption.
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