A fault (blue lines) is embedded in a heterogeneous environment. The EQ preparation process at the ﬁrst stage concerns the fracture of a disordered medium surrounding over a critical circle (Bowman et al., 1998; Sammis and Sornette, 2002) the major fault emitting the MHz EME which can be described by means of a phase transition of second order. The symmetry breaking signalizes the transition from the phase of non-directional, almost symmetrical, cracking distribution to a directional localised cracking zone along the direction of the fault. The EQ is inevitable if and only if the asperities break (green highlighted area), emitting the kHz EME during the second stage, and then an EME silence follows.