The supply rates of basaltic magma to volcanoes restrict the flow rate
s within their mantle sources. Layered source regions consisting of al
ternating layers of melt and residuum have permeabilities that are ord
ers of magnitude larger than percolative sources. Relevant supply rate
s for Hawaiian volcanoes are obtained for source permeabilities within
the range 10(-4)-10(-2) cm(2) The results are within the range for la
yered sources, suggesting that a layered source is a physically viable
model for Hawaiian plume sources.