Table A5.

List of symbols for the physical parameters used in thermodynamic calculations and geophysical modelling

SymbolUnitsDescription
Thermodynamics
GraphickJ mol−1Gibbs free energy at the P and T of interest
GraphickJ mol−1Gibbs free energy at 1 bar and T of interest
RJ mol−1K−1Gas constant
KiEquilibrium constant for a generic reaction i
ΔVJ bar−1Difference of the molar volumes of the products minus those of the reactants opportunely expanded and compressed at P and T of interest
aiActivity of a generic phase i (calculated according to solution models; see text)
GraphicbarOxygen fugacity
GraphicMole fraction of water in the melt
GraphicMole fraction of CO2 in the melt
Geophysical parameters
Qdegasm3 s−1Total magma degassing rate
MSg mol−1Sulphur molecular mass
Graphicg mol−1Sulphur dioxide molecular mass
Graphickg s−1Sulphur degassing rate
ρMkg m−3Density of the magma
Qin–steadym3 s−1Magma input rate during steady state
Qin–exm3 s−1Magma input rate in excess
Vin–steadym3Magma volume entering in the degassing zone during steady state
Vin–exm3Magma volume in excess entering in the degassing zone
Voutm3Generic volume transferred outside the chamber
VRm3Total volume of the reservoir
TdaysTime since the beginning of eruption
τdaysTime constant of the exponential decay
Cm3 Pa−1Capacity of the reservoir
RePa s m−3Resistance of the conduit
ρekg m−3Density of the erupted magma
P0PaInitial overpressure
βRPa−1Wallrock compressibility
βMPa−1Magma compressibility
ρlkg m−3Density of the liquidus
ρgkg m−3Density of the gas mixture