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18.2 - Eruptions

18.2 - Eruptions. Making Magma. Activity depends on ____________ of magma Lava can be thin & __________ or ___________ & lumpy. Magma. Temperature Most rocks melt between _______-1200 °C In Crust & Upper _____________ Pressure

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18.2 - Eruptions

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  1. 18.2 - Eruptions

  2. Making Magma • Activity depends on ____________ of magma • Lava can be thin & __________ or ___________ & lumpy

  3. Magma Temperature • Most rocks melt between _______-1200 °C • In Crust & Upper _____________ Pressure • Increase with ________ because of _________ of rocks • High pressure increases ___________ temperature

  4. Composition of Magma Amount of Gas & Silica • Increase gas dissolved = ______________ explosiveness • _____________+ gases = carbon dioxide, water vapor, sulfur oxide, sulfuric acid • Water vapor determines _________ magma forms • Water vapor ______________ melting temperature

  5. Composition ________________ = Resistance to flow • Temperature & silica content affect ____________ • High viscosity = __________ magma • High silica = _____________ & sticky • Traps gases, produces explosive eruptions • Low silica = __________ & runny • Flow easily, produce quiet, non-explosive eruptions

  6. Types of Magma - Basaltic • Less then __________ silica content • __________-viscosity magma • Gas ____________ escapes • ______________ eruptions • Ex: Kilauea & Mauna Loa http://media-2.web.britannica.com/eb-media/31/20231-004-008EFA7E.jpg

  7. Types of Magma - Andesitic • 50-_________ silica content • Oceanic-continental ___________ zones • _______________ viscosity • _______________ explosiveness • Send __________ volumes of ash & debris • Ex: Colima Volcano in Mexico http://images.livescience.com/images/050531_colima_volcano_04.jpg

  8. Types of Magma - Rhyolitic • More than _________ silica content • Magma ___________ with water and silica • _____________ viscosity • ____________ volumes of gas trapped • ___________ explosive

  9. Explosive Eruptions • If lava is too ____________ to flow, pressure builds up until an __________________ • _____________ = ash and pieces of solidified lava or pieces of crust • Classified by _________ • ________ = smallest tephra, diameter is less then 2 mm • Blocks = largest tephra

  10. Ash • Can ________ into atmosphere • _________ sulfuric acid droplets remain in stratosphere and ____________ sun’s rays and ______________ global temperature http://geology.com/articles/volcanic-ash/volcanic-ash-column.jpg

  11. Pyroclastic Flows • Tephra + gases • VERY ___________ http://vulcan.wr.usgs.gov/Imgs/Jpg/MSH/Images/MSH80_pyroclastic_flow_from_st_helens_crater_08-07-80.jpg

  12. In-Class Assignment • 18.2 Study Guide WKT

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