The cellular automata technique is used to investigate metastable magn
etic structures of a square lattice of spins with an Ising antiferroma
gnetic interaction between nearest and next-nearest neighbours. A dyna
mic phase diagram is introduced, where an evolution rule is ascribed t
o each set of values of the Hamiltonian parameters. This diagram also
includes a dynamic spin-glass state, formed by instabilities of the ma
gnetic structure.