vulcanicity 2

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  • Created by: Sharon
  • Created on: 29-12-15 12:45
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  • Vulcanicity (2)
    • Long term forecasting
      • Geological history eg type of hazard and frequency by radiometric age dating.
      • Once assessment made forecast what areas affected and how affected.
      • this info combined with knowledge frequency and current surface, make volcanic hazard maps-plan evacuation,rescue and recovery.
    • Short term
      • Earthquakes- as magma moves to surface fractures rock =earthquakes. more earthquakes=volcanoe eruption
      • Ground deformation- structure inflates as magma enters (tilt metres)
      • Change heat flow- as magma rises water temp increases (infared)
      • Change gas composition- prior to eruption increase in HCL & SO2.
    • Primary effects
      • Lava flows- strombolian and hawaiin eruptions, slow and people time - can destroy anything
      • Pyroclastic flows- cause death by suffocation and burning few can escape.
      • Ash falls- twice density of snow dont melt, can collapse roofs. far from eruption, kill vegetation therefore livestock - years after
      • Gases- predominant is H20. others- HCL,H2S, HF,CO2. Sulphur along side ash reflect radiation back to space=cooling few years at most.
    • Secondary & Tertiary
      • Mudflows (lahars)- water and loose ash. hot or cold, high velocity.
      • Avalanches & landslides- over steepened slows become unstable not necessarily due to eruption
      • Flooding- drainage blocked by pyro and lava flows, melting of snow.
      • avalanche, landslide, pyro, entering eater = tsunami
      • Earthquakes- accompany eruptions as break through litosphere.
    • WHY LIVE THERE???
      • New land
      • Fertile soil
      • Mineral resource
      • Industrial products
      • Spas
      • Tourism

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