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PostPosted: February 25th, 2013, 5:46 pm
by Jessica
A volcano is a manifestation at the surface by way of the way of the release of a solid/liquid/gas due to internal heat processes of a planet.

Two prerequisites needed for volcanic activity
  • something to melt
  • source of heat

What are the sources of heat?
  • thermal energy being dissipated in the form of heat loss (convection, conduction, radiation)

Volatile effects on a melt
  • most common volatiles: H[sub]2[/sub]O, CO[sub]2[/sub], SO[sub]2[/sub], CO, H[sub]2[/sub]S...
  • in general, all volatile species are lumped into one percent value for the melt

Viscosity (η)
  • internal resistance to flow (strain) by a substance when subjected to shearing (stress)
  • i.e. "slugginess" of a fluid
    • dependence on other factors in the material
      • temperature, phenocryst/bubble content, volatile content, SiO[sub]2[/sub], pressure
        • increase in SiO[sub]2[/sub], increase in viscosity
        • increase in temperature, decrease in crystallization, # of atomic bonds and viscosity