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Volcanoes

Volcanoes. Tungerahua Volcano, Ecuador Picture by Alcinoe Calahorrano. Volcanoes form around vents that release magma onto the Earth’s surface. Vents. Lava. Magma chamber. Volcanic Eruptions . Lava flow. Lava fountain. Nonexplosive Eruptions Explosive Eruptions. What is Lava ?

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Volcanoes

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  1. Volcanoes Tungerahua Volcano, Ecuador Picture by Alcinoe Calahorrano

  2. Volcanoes form around vents that release magma onto the Earth’s surface. Vents Lava Magma chamber

  3. Volcanic Eruptions Lava flow Lava fountain • Nonexplosive Eruptions • Explosive Eruptions What is Lava? -magma that flows onto the Earth’s surface

  4. The Composition of Magma Determines whether it is explosive or not! water • High water content • More likely to be !!! • High content • More likely to be !!! • Why? • Silica has a thick, stiff consistency • Flows slowly • Tends to Harden in the volcano’s vent EXPLOSIVE silica EXPLOSIVE

  5. What Erupts from a Volcano? Blocky lava Lava can be thick or thin. Pahoehoe Aa Pillow lava

  6. What Erupts from a Volcano? • Pyroclastic material • Rock fragments created by eruptions • magma explodes from volcano and solidifies in the air • existing rock is shattered by powerful eruptions EXPLOSIVE Lapilli Volcanic bombs Volcanic blocks Volcanic ash

  7. How do volcanoes affect the Earth? • Flows and Fallouts • hot ash can flow really quickly • Knock down buildings • Dam rivers (flooding/drought) • Kill crops and livestock • Climatic Changes • Ash & Gases can block sunlight • Drop average global temperature noticeably

  8. Types of Volcanoes Shield volcano Cinder cone volcano Composite volcano

  9. Craters, Calderas, and Lava Plateau • Crater • From explosions of material out of the vent and the collapse of material back into vent • Caldera • Much larger depression that forms when magma chamber empties and its roof collapses • Lava Plateau • Forms when lava erupts from long cracks, or fissures, and spreads out evenly (thousands of km)

  10. What causes volcanoes? • The Formation of Magma • Mantle rock melts when the temperature increases • or the pressure decreases.

  11. What causes volcanoes? • Where Volcanoes Form • Tectonic Plate Boundaries!!! ~75% world’s active volcanoes in Ring of Fire

  12. What causes volcanoes?

  13. What causes volcanoes? Hot Spots

  14. How do volcanologists predict eruptions? • Measuring Small Quakes • Before eruption, increase in number & intensity • Measuring Slope • Bulges may form with magma (tiltmeter) • Measuring Volcanic Gases • Outflow of volcanic gases • Sulfur dioxide, carbon dioxide • Measuring Temperature from Orbit • Measure changes in temperature over time

  15. You should not be a Volcanologist if…. • You don’t like hiking, backbacking, rockclimbing, etc. • You are not interested in experiencing extreme temperatures and heights. • If you don’t like to travel to incredible places and see breathtaking views of the world. Robert McGimsey USGS A. Ozerov

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