  It has recently been found that the evolution of the preparation of a strong
earthquake (EQ), as it is monitored through fracture-induced electromagnetic
emissions (EME) in the MHz band, presents striking similarity with the
evolution of a thermal system as temperature drops, since distinct steps of the
evolution of the phenomenon of spontaneous symmetry breaking (SSB) can be
identified. Here, the study of fracture-induced EME in the MHz band in analogy
to thermal systems is extended to the phase of local fracture structures that
follow after the SSB (and the occurrence of the main EQ). By comparing
fracture-induced MHz EME associated with the strongest EQs (Mw=6.9) that
occurred in Greece during the last twenty years with the 3D Ising model, a way
to distinguish whether a possible identification of post-SSB power-laws
immediately after a very strong EQ is a sign for the preparation of a new
strong EQ or not is provided. In the suggested approach, the time series
analysis method known as the method of critical fluctuations is used, enhanced
by the autocorrelation function, while the role of the latter proves to be
decisive.
