Question about melt transport in Melt Global Material Model

Hi All,

I noticed from the global melt parameter file (global_melt.prm) the comment addressing the Reference bulk viscosity parameter:

# The bulk viscosity describes the resistance of the rock to dilation
# and compaction. Melt can only flow into a region that had no melt
# before if the matrix of the solid rock expands, so this parameter
# also limits how fast melt can flow upwards.
# The bulk viscosity is computed as the reference value given here times
# a term that scales with one over the porosity. This means that for zero
# porosity, the rock can not dilate/compact any more, which is the same
# behavior that we have for solid mantle convection.

The melt global material model is incompressible. Does this mean that melt global does not allow melt to migrate through material that has not melted before (where porosity = 0)?

Thanks!
Micah