This experimental work consists in a study of the influence of horizontal sinusoidal vibrations on the behaviour of a 31) sand granular medium. A transition from jammed or glassy states to a fluidized state has been observed for critical acceleration increasing with the frequency. Convective patterns have been encountered and characterised: two cylindrical counter-rotating rolls have been observed in the top of the packing. In addition, for high acceleration values, more complex patterns appear. The free surface at the top of the packing presents different shapes called "dome", "dromedary" or "camel" depending on acceleration. One or three humps can be found. Analysis of grain movements and velocities along the walls of the container has been carried out and show that a stationary state can be reached after a transient regime. Finally the mechanisms of material transport through convective motion have been discussed. (C) 2008 Elsevier B.V. All rights reserved.