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Parts of a Volcano

Parts of a Volcano. 1. Gas emission : various gases such as CO2, H2O, nitrogen, and lesser gases such as chlorine, hydrogen, and argon. 2. Crater: depression connected to magma chamber via a pipe aka caldera 3. Lava : magma that has reached the surface 4. Rock

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Parts of a Volcano

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  1. Parts of a Volcano • 1. Gas emission: various gases such as CO2, H2O, nitrogen, and lesser gases such as chlorine, hydrogen, and argon. • 2. Crater: depression connected to magma chamber via a pipe aka caldera • 3. Lava: magma that has reached the surface • 4. Rock • 5. Vent or pipe: conduit that connects magma chamber to the crater • 6. Magma chamber: area where magma accumulates within the volcano • 7. Fumorale: vent that emits only gases

  2. Anatomy Of A Volcanic Eruption! • Intense heat from magma cracks the rocks near the surface. The cracking rock produces an earthquake!! • Hot blasts of high pressure gases expand the cracks and develop a passage to the surface. • Hot gases with rock fragments create a larger conduit or pipe. Volcanic pipes are created due to increase in pressure. A bulge is created due to gas build up. • Pipes enlarge, magma moves upward to produce an eruption. • Pipes can become clogged with cooled magma and debris. Gas pressure can build up an cause another eruption.

  3. What determines how violent a volcano’s eruption will be? • The viscosity of the magma influences the violence of the eruption.

  4. What is viscosity? • The resistance of a material to flow. • A very viscous material is very thick and flows slowly. • When thinking of a volcano…the more viscous the magma, the explosive the eruption!

  5. What influences the viscosity of magma? • Temperature • Chemical composition of the magma • Amount of dissolved gases (H2O and CO2)

  6. Temperature • Fluidity (flow) and mobility (movement) is strongly influenced by temperature. • Cool lava congeals (becomes solid) just like making jello. The mobility and flow stops.

  7. Magma’s Chemical Composition • Viscosity is directly related to silica content. • The more silica-- the greater the viscosity. • Flow is slowed due to the long chains of silica molecules. • Felsic(high in silica) very viscous, short, thick flows. • Mafic (low in silica) very fluid, travels long distances

  8. Dissolved Gases • Dissolved gases increase the fluidity of magma. • Escaping gases expand as pressure decreases. • This provides the force to propel molten rock.

  9. Non-explosive Eruptions • Fluid lava (basalt) magma allows for expanding gases to be released with ease. • Release huge amount of lava • Most common type of volcanic eruption • The northwest U.S. region, the Hawaiian Islands and the mid-ocean-ridge are all examples of non-explosive eruptions.

  10. Explosive Eruptions • Highly viscous magmas explosively expel jets of hot ash, gases, and other debris. • Instead of producing lava flows, explosive eruptions cause molten rock to be blown into tiny particles (thousands of fragments of glass) • Examples of explosive eruptions: Mt. St. Helen’s, Mt Pinatubo in the Philippines

  11. Effects of Volcanic Eruptions • Volcanic ash and gases spread throughout the atmosphere. • They can block out enough sunlight to cause global temperatures to drop.

  12. Measuring the Intensity Mercalli Scale measures the degree to which people feel the EQ and the amount of the damages caused by the EQ.

  13. Effects of the Mount Tambora eruption (1815) on humanity: • Ash blanketed the skies of Indonesia and caused 3 days of total darkness. • Estimated that 12,000 people died directly from the blast. • 80,000 people died from the resulting hunger and disease. • caused global temperature to drop • affected the global climate a year later • affected temperatures enough to cause food shortages in N.America and Europe • The summer was called the Summer of Starvation.

  14. Types of Volcanoes: • A plume is a hotspot that erupts as a volcano. • Magma comes from deep within the mantle. • As crust moves, the volcano will move off the hot spot and become extinct. • A new volcano will form. • example: Hawaiian Islands • Plumes are volcanically active places on the Earth’s surface that are far from plate boundaries. • Some scientists believe that hot spots are magma plumes along cracks in the plates. We know that hot spots always from big chains of islands. • An example of an unusual CONTINENTAL hotspot is Yellowstone National Park.

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