  One of the main concerns in extreme value theory is to quantify the
dependence between joint tails. Using stochastic processes that lack
flexibility in the joint tail may lead to severe under-or over-estimation of
probabilities associated to simultaneous extreme events. Following recent
advances in the literature, a flexible model called max-mixture model has been
introduced for modeling situations where the extremal dependence structure may
vary with the distance. In this paper we propose a nonparametric model-free
selection criterion for the mixing coefficient Our criterion is derived from a
madogram, a notion classically used in geostatistics to capture spatial
structures. The procedure is based on a nonlinear least squares between the
theoretical madogram and the empirical one. We perform a simulation study and
apply our criterion to daily precipitation over the East of Australia.
