The steadily increasing amount of information available today on the natural electromagnetic emission (EME) of the radio frequency band associated with seismic events raises the problem of the origin of this phenomenon. A natural hypothesis is that EME is due to earthquake preparation processes. The present paper is concerned with substantiating a model that postulates EME to be caused by cracking of surficial crustal layers in the zone of earthquake preparation. The crust is assumed to have ordered hierarchical structure. Individual elements of that structure are formed of blocks of different scales and obey principles of similarity. Between the blocks are soft interlayers with a finite strength limit. A regular periodic structure with a cubic lattice is studied. As a result, EME intensity as a function of magnitude is evaluated. Methodological recommendations are given for organization of field observations of EME in relation to earthquake prediction.