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C6S2

C6S2. Volcanic Eruptions. Magma Reaches Earth’s Surface. Inside a Volcano. Magma Chamber – The pocket beneath a volcano where magma collects Pipe - A long tube through which magma moves from the magma chamber to Earth’s surface. Vent – Opening through which magma leaves a volcano.

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C6S2

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  1. C6S2 Volcanic Eruptions

  2. Magma Reaches Earth’s Surface

  3. Inside a Volcano • Magma Chamber – The pocket beneath a volcano where magma collects • Pipe - A long tube through which magma moves from the magma chamber to Earth’s surface. • Vent – Opening through which magma leaves a volcano. • Lava Flow – Area covered by lava from a volcano’s vent. • Crater – A bowl-shaped area that forms around a volcano’s central opening.

  4. What Happens when a volcano erupts? • When a volcano erupts, the force of the gases push magma from the magma chamber through the pipe (main vent) until it flows or explodes out the vent (throat)

  5. Kinds of Volcanic Eruptions

  6. The Properties of magma determine how a volcano erupts. • There are two types of eruptions • Quiet eruptions • Explosive eruptions • Type of eruption is dependent on the magmas silica content and whether the magma is thin and runny or thick and sticky.

  7. Silica • A material found in magma that is formed from the elements oxygen and silicon.

  8. Quiet Eruptions • A volcano erupts quietly if its magma is low in silica. • Low silica magma is thin and runny and flows easily. • The gases bubble out gently. • Two different types of eruptions that differ in temperatures • Pahoehoe – fast moving, hot lava that is thin and runny. • Aa – thicker than Pahoehoe

  9. Lava from Pahoehoe Looks like a solid mass of wrinkles and ropelike coils

  10. Lava form Aa . When hardens it forms a rough surface consisting of jagged lava chunks

  11. Explosive Eruptions • A volcano erupts explosively if its magma is high in silica. • High Silica magma is thick and sticky. • It plugs up the pipe like a cork, trapping the dissolved gases, which builds up pressure until it explodes. • Explosive eruptions break lava into fragments that quickly harden into pieces of different sizes. • Ash – small specks of dust • Cinders – pebble-sized particles • Bombs – large pieces that range from the size of baseballs to the size of a car.

  12. Pyroclastic Flow • An explosive volcanic eruption of ash, cinders, bombs and gases.

  13. Rock From Volcanoes • Pumice – forms when gas bubbles are trapped in fast-cooling lava, leaving space in the rock. • Obsidian – glossy surface like glass

  14. Stages of Volcanic Activity

  15. What are the volcano’s stages of activity? • Geologists often use the terms active, dormant, or extinct to describe a volcano’s stage of activity.

  16. What is the difference between an active, erupting, dormant and extinct volcano? • An active volcano is a volcano that has had at least one eruption during the past 10,000 years. An active volcano might be erupting or dormant. • An erupting volcano is an active volcano that is having an eruption... • A dormant volcano is an active volcano that is not erupting, but supposed to erupt again. • An extinct volcano has not had an eruption for at least 10,000 years and is not expected to erupt again in a comparable time scale of the future.

  17. Geyser • Is a fountain of water and steam that erupts from the ground. Example: Yellowstone

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