  We study the ferromagnetic Ising model on the Sierpinski gasket (SG), where
the spin-spin interactions depends on the direction. Using the renormalization
group method, we show that the ratios of the correlation lengths restore the
isotropy of the lattice as the temperature approaches zero. This restoration is
either partial or perfect, depending on the interactions. In case of partial
restoration, we also evaluate the leading-order singular behavior of the
correlation lengths.
