Volcanoes

[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