Where are they?How do they happen?BasaltShield VolcanoFlood BasaltAndesiteCinder ConesComposite ConesRhyolitePlug DomeOther HazardsNuee ArdentLaharGEO 155 1st Edition Lecture 25Last Lecture Erosion on SlopesOutline of Current LectureI. Volcanoesa. Backgroundb. Basaltc. Andesited. Rhyolitee. Other HazardsCurrent LectureWhere are they?- Spreading centers- “Hot Spots”- Subduction ZoneHow do they happen?- Type of eruption and landforms created depends on molten composition- Spectrum:o Basalt: Low silicon High iron and magnesium Very hot FluidThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Dark color Oceanico Andesite: In between characteristics of basalt and rhyoliteo Rhyolite: High silicon Low magnesium and iron Less hot Viscous Light color ContinentalBasaltShield Volcano- Gentle eruption- More liquido Flows easilyo “effusive”- Relatively slow- Broad, gentle slope- Example: Hawaii’s Big IslandFlood Basalt- Several vents close together- RareAndesiteCinder Cones- More viscouso Can lead to clogged vent Explosive eruptionso “Pyroclastic”- Cools as it erupts- Small rocks and bouldersComposite Cones- Altervernating explosive or effusive eruptionso Explosive – build loose coneo Effusive – bind sediment- Tall - Example: Mt. FujiRhyolitePlug Dome- Very viscous- Can get cinder cones- If flowing, can’t travel far- High likelihood of eruptionOther HazardsNuee Ardent- Clogged vent- Can go miles in a few secondso “Pyroclastic flow”- Example: Mt. PeleLahar- Volcanic mudflow- Mix of ash and watero Melted alpine glaciers, post eruption storms- Fast moving, wet cement- Tends to move toward
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