  In this paper we investigate on uniqueness properties of solutions to the
surface electromigration (SEM) equation, which is a generalisation of the more
classical Zakharov-Kuznetsov equation of plasma physics with non-local
perturbation terms. We will show that if the difference of two solutions has a
sufficiently strong spatial decay at two different instants of time, then the
two solutions coincide on the whole interval of time.
