  This paper considers a sandpile model subjected to a sinusoidal external
drive with the time period $T$. We develop a theoretical model for the Green
function in a large $T$ limit, which predicts that the avalanches are
anisotropic and elongated in the oscillation direction. We track the problem
numerically and show that the system shows additionally a regime where the
avalanches are elongated in the perpendicular direction with respect to the
oscillations. We find a transition point between these two regimes. The power
spectrum of avalanche size and the grains wasted from the parallel and
perpendicular directions are studied. These functions show power-law behaviour
in terms of the frequency with exponents, which run with $T$.
