  The article determines the asymptotic shape of the extremal clusters in
stationary regularly varying random fields. To deduce this result, we present a
general framework for the Poisson approximation of point processes on Polish
spaces which appears to be of independent interest. We further introduce a
novel and convenient concept of anchoring of the extremal clusters for
regularly varying sequences and fields. Together with the Poissonian
approximation theory, this allows for a concise description of the limiting
behavior of random fields in this setting. We apply this theory to shed
entirely new light on the classical problem of evaluating local alignments of
biological sequences.
