The recently introduced concept of k-power domination generalizes domination and power domination, the latter concept being used for monitoring an electric power system. The k-power domination problem is to determine a minimum size vertex subset S of a graph G such that after setting X=N[S], and iteratively adding to X vertices x that have a neighbour v in X such that at most k neighbours of v are not yet in X, we get X=V(G). In this paper the k-power domination number of SierpiA"ski graphs is determined. The propagation radius is introduced as a measure of the efficiency of power dominating sets. The propagation radius of SierpiA"ski graphs is obtained in most of the cases.