  We analyze the presence of substructures in a set of 48 galaxy clusters, by
using galaxy positions and redshifts. We use a multi-scale analysis which
couples kinematical estimators with the wavelet transform. 14% of our clusters
are strongly substructured (i.e. they are bimodal or complex) and 24% of the
remaining unimodal clusters contain substructures at small scales. Thus, in
substantial agreement with previous studies, about one third of clusters show
substructures. In unimodal clusters the presence of substructures does not
affect the estimates of both virial masses and velocity dispersions, which are
generally in good agreement with the X-ray temperatures. Thus, unimodal
clusters are not too far from a status of dynamical equilibrium. On the
contrary, velocity dispersions and masses for some bimodal or complex clusters
strongly depend on whether they are treated as single systems or as sums of
different clumps and X-ray temperatures and velocity dispersions may be very
different.
