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Volcanoes

Volcanoes. You need to know: There are 3 types of volcanoes which are determined by the lava eruptions that form them Types of eruptions are determined by the composition of the lava and gasses There are many different things that come out of a volcano Volcanoes occur at different places.

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Volcanoes

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  1. Volcanoes

  2. You need to know: • There are 3 types of volcanoes which are determined by the lava eruptions that form them • Types of eruptions are determined by the composition of the lava and gasses • There are many different things that come out of a volcano • Volcanoes occur at different places

  3. What is Viscosity? • A substances ability to RESIST flowing

  4. 3 Types of Volcanoes • Shield Volcano (low viscosity basaltic lava) • TALL, FLAT, mostly grow from the ocean floor • Examples: Hawaii, Iceland

  5. 3 Types of Volcanoes • Cinder Cone (gas-rich basaltic magma) • Made mostly from cinders and ash, normally do not have lava flow from them • Erupt only once, commonly found in lava fields or on the sides of larger volcanoes – SMALL, STEEP

  6. 3 types of volcanoes • Composite Cones (gas and silica-rich andesitic magma) • TALL, STEEP, very common along the ring of fire, explosive eruptions • Very viscous lava that only travels a short distance creating the steep slopesAND layers of Cinder (Mount Ranier, Mount St. Helens, Mount Vesuvies

  7. Types of Eruptions • Quiet Eruptions – 1) Low viscosity magma (flows easily) - high temperature, low silica content, mafic 2) Low gas pressure - Carbon dioxide and water vapor escape easily • Violent Eruptions – 1) High viscosity magma (does not flow easily) - low temperature, high silica content, felsic 2) High gas pressure - Carbon dioxide and water vapor can’t escape

  8. Volcanic Material • Lava Flows 2) Gases - Carbon dioxide, water vapor, nitrogen, sulfur, chlorine, hydrogen, argon 3) Pyroclastic Material • Ash and dust (small) • Lapilli or cinder (medium) • Blocks and Bombs (large)

  9. Anatomy of a Volcano • Crater • Vent, Pipe, Neck (through which magma reaches the surface) • Caldera (collapsed magma chamber)

  10. Dangers of Eruptions • Pyroclastic Flows - hot gases, glowing ash, large rock fragments that travel at 300 mph • Lahars – destructive mudflows resulting from water saturated volcanic debris

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