  We propose a possible particle physics explanation of the non-observation of
muon neutrino events at IceCube coincident with GRB gamma ray at the rates
predicted by the standard Bahcall-Waxman model, in terms of neutrino
oscillations. Our model is based on assuming that (a) all neutrinos are
pseudo-Dirac particles and (b) there exists a mirror world interacting
gravitationally with the observed world. This scenario has three sterile
neutrinos associated with each flavour of ordinary neutrinos. Very tiny mass
splitting between these neutrinos is assumed to arise from lepton number
violating dimension five operators suppressed by the Planck scale. We show that
if a mass splitting of 10^(-15) eV^2 is induced between the four mass
eigenstates of a given species, then its flux will be suppressed at IceCube
energies by a factor of 4 which could be the explanation of the IceCube
observation that the muon neutrino flux is lower than expected. Hierarchies in
mass splitting among different flavours may result in different amount of
suppression of each flavour and based on this, we predict a difference in the
flavour ratios of the observed neutrinos which is significantly different
compared to the standard prediction of nu_e:nu_mu:nu_tau=1:1:1 which could
serve as a test for this model.
