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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  • When will Yellowstone erupt?

    Q: When will Yellowstone erupt?

    A: Predicting when the next eruption will occur is difficult; however, the National Science Foundation estimates the next major eruption shouldn't happen for at least another one million years. The next eruption may dump several inches of ash over a large portion of the United States and could change Earth's climate.
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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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  • How do volcanoes affect the environment?

    Q: How do volcanoes affect the environment?

    A: An erupting volcano emits gases and dust particles that can cause profound changes in weather and climate throughout the world. Volcanism also affects the environment by producing acid rain and making ocean water warmer.
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  • What are the main features of a volcano?

    Q: What are the main features of a volcano?

    A: The main features of a volcano include a vent, a summit crater and a magma chamber. The vent is an opening through which volcanic material is erupted. Volcanoes can have more than one vent. The summit crater is the large concave opening that holds the central vent at the top of the volcano. The magma chamber is the large pool-like structure inside the volcano that holds the magma.
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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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  • Where is Krakatoa located?

    Q: Where is Krakatoa located?

    A: Krakatoa is a volcanic island located in the Sunda Strait between Java and Sumatra in Indonesia. The island measures 3 miles wide by 5 1/2 miles long.
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  • What is a mudflow on a volcano called?

    Q: What is a mudflow on a volcano called?

    A: Mudflow on a volcano is called lahar and is typically caused by heavy rains during or after volcanic eruptions. Lahars can also occur when nearby ice or snow melts, carrying ash and rock debris down a volcano's slopes.
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  • What is an active volcano?

    Q: What is an active volcano?

    A: An active volcano is one that has had at least one eruption in the past 10,000 years. An active volcano can be dormant or erupting.
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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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  • How does a volcano form?

    Q: How does a volcano form?

    A: A volcano forms when a vent in the Earth's crust allows magma to well up from below. The magma fills a void underneath the surface, and when it builds up enough pressure, it bursts through to the surface. As the magma cools, it hardens into rock, and multiple eruptions may build up the mountainous form of a volcano.
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  • What is a main vent in a volcano?

    Q: What is a main vent in a volcano?

    A: The main vent of a volcano is the outlet chamber in the Earth's crust that allows hot magma to reach the surface. While secondary vents may form to alleviate the pressure caused by a magma chamber, the main vent is responsible for giving volcanoes their familiar cone shape.
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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 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 is the top of a volcano called?

    Q: What is the top of a volcano called?

    A: The top of a volcano is called the crater. A volcano is shaped like an inverted cone, and the tip of the cone is the crater. The crater is the opening of the vent in a volcano through which the molten magma or the lava is ejected.
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  • How do volcanoes change the Earth's surface?

    Q: How do volcanoes change the Earth's surface?

    A: Volcanic eruptions involve the incursion of liquid magma into a physical environment, and the effects include major transformations, ranging from the formation of new land to the destruction of the viability of an existing environment. Just one example of the creation of new land comes from the Hawaiian Islands, which appeared as magma cooled into land after eruptions.
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  • When did Mount Saint Helens erupt?

    Q: When did Mount Saint Helens erupt?

    A: Mount St. Helens' most significant eruption in modern times occurred on March 20, 1980. It was followed by additional eruptions between Dec. 7, 1989 to Jan. 6, 1990, Nov. 5, 1990 to Feb. 14, 1991, Oct.11, 2004, Mar. 8, 2005, and between Jan. 16, 2008 to July 10, 2008.
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  • What causes a volcano to erupt?

    Q: What causes a volcano to erupt?

    A: 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 causes volcanic eruptions?

    Q: What causes volcanic eruptions?

    A: Volcanic eruptions occur when magma builds up beneath the Earth's crust and forces its way to the surface. Natural vents in the crust allow magma passage to the surface, and eruptions occur when the magma that forms is less dense than the material above it, causing it to flow upward. In some cases, this flow is slow and steady, but it can also be rapid and violent.
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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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