  Astrophysical sources of ultrahigh energy neutrinos yield tau neutrino fluxes
due to neutrino oscillations. At neutrino energies in the EeV range, radio
Cherenkov detection methods show promise for detecting these fluxes. We
quantify the tau neutrino contributions to the signal in, for example, a
detector like the Radio Ice Cherenkov Experiment (RICE) for a Z-burst flux
prediction. Tau neutrino regeneration in transit through the Earth, including
energy loss, is evaluated.
