  We study the longitudinal development of hadronic showers in ice for energies
up to 100 EeV and its implications for radio and optical Cherenkov emission. A
small fraction of showers induced by primaries of energy above 1 EeV is shown
to display the characteristic elongation associated to the Landau Pomeranchuck
Migdal (LPM) effect. The rest look like ordinary showers because the highest
energy $\pi^0$'s interact instead of decaying in two photons. The LPM effect
observed in this fraction of the showers is mainly due to $\eta$ and $\eta '$
production and decay. We give parameterizations for the total and excess charge
tracklengths and for the amplitude and angular spread of the electric field
spectrum in the Cherenkov direction. Implications for neutrino detection are
briefly addressed.
