Ultrahigh Energy Neutrinos in the Light of SuperK

We propose a novel approach for studying neutrino oscillations with extragalactic neutrinos. We show that measurement of the neutrino induced upward hadronic and electromagnetic showers and upward muons could be used to detect $\nu_\mu \to \nu_\tau$ oscillations. We find significant signal to background ratios for the hadronic/electromagnetic showers with energies above 10 TeV to 100 TeV initiated by the extragalactic neutrinos. We demonstrate that a kilometer-size neutrino telescope has a very good chance of detecting neutrino oscillations.