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Earth 2
Need to look at Pow slides because did not use those
| Question | Answer |
|---|---|
| What is the relationship between volcanoes and earthquakes | movement of magma breaks rock causing earthquakes, tectonic plate dynamics cause seismic and volcanic activity |
| Where are the biggest volcanic risks located? | High probability of phenomenon close to high populations of humans, ring of fire, central Atlantic, East African Rift |
| Where do we find stratovolcanoes? | Ring of fire (subduction) |
| Where do we find Shield Volcanoes? | Intracontinent (hot spots?) and MORs |
| What two ways are there to melt the mantle? | Decompression melting and Flux melting |
| Decompression melting | Lower pressure at same temperature allows the energetic molecules to break from one another to form a liquid |
| Flux melting | Introduction of volatiles like water and CO2 to mantle rocks lowers the melting temperature |
| Where specifically do volcanoes happen? | Zones of crustal convergence |
| Where does flux melting happen? | At subduction zones |
| Flux melting details | Down going slab brings water and other volatiles with it. Volatiles diffuse into the mantle, lowering the melting point. Partial melting takes place creating magma. Magma rises creating an arc of volcanic activity |
| Another name for Felsic | rhyolitic |
| Another name for intermediate composition of magma | andesitic |
| Felsic and Intermediate composition magma/lava | Higher silica and lower temperature makes the lava viscous, higher viscosity leads to more explosive eruptions. |
| Stratovolcano: composition | alternating layers of ash and lava. Felsic and intermediate compositions |
| How does Felsic and Intermediate composition magma/lava work? | Viscous magma is trapped in volcano neck. Decreased pressure allow gases to exsolve and rapidly expand. Pressure builds to explosion. Hot ash flows can move very fast and be deadly |
| Intermediate Magma and lava flow | Associated with subduction. Mafic flux melting mixing with partial melting of continental (felsic) crust gives intermediate composition. Higher silica and volatiles make magma more viscous so more explosive eruptions |
| Decompression melting described | mantle material rises, pressure decreases allowing kinetic molecules to separate from each other. Solid transforms into liquid |
| Mafic (Basaltic) Composition magma/lava | Higher iron and lower silica makes magma/lava much less viscous, lava spreads out further creating broad, low angle volcanoes (shield volcanoes) |
| Mafic eruptions and lava flow | much gentler, less explosive (unless water is involved). Aa and Pahoehoe |
| Pahoehoe | A mafic eruption. Low viscosity, runny, ropey, flow |
| Aa | A mafic eruption. High viscosity, chunky, rugged flow |
| VEI | Volcano Explosivity Index. A relative measure of explosiveness of volcanoes. Measured by estimated amount of erupted material. The bigger the event, the fewer times they happen |
| Hazard: Lava flows | Slow enough that people can usually evacuate. Houses and roads are not so lucky. Not stoppable. Covers everything with feet of solid rock |
| Hazard: Pyroclastic flow | Fire piece of rock. 200-800 degrees. Travel downslope at about 80 km/h. Deadly to most organisms. Melt snow/ice quickly , so can cause flash flooding |
| Hazard: Tephra | Ash clouds and ash fall. Covers everything, makes breathing difficult. Interrupt air transport |
| Hazard: Pyroclastic debris | Ash, lapilli, Volcanic bomb, volcanic blocks |
| Hazard: Lahar | When ash and water mix. If rain saturates ash or lava melts glaciers or snow at the top of a volcano, it can cause large and dangerous mudflows. |
| Hazard: Volcanic gases | steam, CO2, sulfur dioxide, hydrogen sulfide, hydrogen fluoride, hydrogen chloride. Can cause asphyxiation, chemical contamination. SO2 in the atmosphere can cause short term global warming |
| Hazard: Carbon Dioxide | Lake Nyos in Kenya. This killed about 2000 people. CO2 is just denser than air and displaced the oxygen, suffocating the O2 organisms. CO2 is NOT poisonous |
| Mitigation research | SU lava project. Different slopes of flow, wet vs dry substrate, lava and ice interactions, lava and water interactions |
| Mitigation monitoring | Volcano observatories, paleo-volcanism. Keep track of all the volcanoes |
| Mitigation monitoring steps 1-2 | 1. Gas composition change can indicate movement of magma. 2. ground tilts or moves to accommodate influx of magma. |
| Mitigation monitoring steps 3-4 | 3. seismometers can sense breaking rocks due to magma migration and vibrations within the magma. 4. Temperature change can indicate magma getting closer to the surface |
| Mitigation monitoring, listening to the pulse of the Earth | 1. Magma moving through underground plumbing system gives characteristic signals. 2. An increase in signal frequency is a good indicator of impending eruption |
Created by:
user-1996284