  The expansion of a magnetized high-pressure plasma into a low-pressure
ambient medium is examined with particle-in-cell (PIC) simulations. The
magnetic field points perpendicularly to the plasma's expansion direction and
binary collisions between particles are absent. The expanding plasma steepens
into a quasi-electrostatic shock that is sustained by the lower-hybrid (LH)
wave. The ambipolar electric field points in the expansion direction and it
induces together with the background magnetic field a fast E cross B drift of
electrons. The drifting electrons modify the background magnetic field,
resulting in its pile-up by the LH shock. The magnetic pressure gradient force
accelerates the ambient ions ahead of the LH shock, reducing the relative
velocity between the ambient plasma and the LH shock to about the phase speed
of the shocked LH wave, transforming the LH shock into a nonlinear LH wave. The
oscillations of the electrostatic potential have a larger amplitude and
wavelength in the magnetized plasma than in an unmagnetized one with otherwise
identical conditions. The energy loss to the drifting electrons leads to a
noticable slowdown of the LH shock compared to that in an unmagnetized plasma.
