  We calculate the expected galactic supernova neutrino signal at large
next-generation underground detectors. At different epochs after the explosion,
the primary fluxes can be quite different. For these primary neutrino fluxes,
spectral splits induced by collective neutrino flavor transformations can arise
for either mass hierarchy in both neutrino and antineutrino channels. We
classify flux models according to the nature and number of these splits, and
calculate the observable electron-neutrino and electron-antineutrino spectra at
Earth, taking into account subsequent matter effects. We find that some of the
spectral splits could occur sufficiently close to the peak energies to produce
significant distortions in the observable SN neutrino signal. The most striking
signature of this effect would be presence of peculiar energy dependent
modulations associated with Earth matter crossing, present only in portions of
the SN neutrino energy spectra demarcated by spectral splits. These signatures
at proposed large water Cherenkov, scintillation, and liquid Argon detectors
could give hints about the primary SN neutrino fluxes, as well as on the
neutrino mass hierarchy and the mixing angle theta_{13}.
