Local stress concentrations in the earth's interior can be adequately described by the dislocation theory of continuous media. Different types of internal failure have stress fields concentrated around them. These fields can be approximated by the appropriate distribution of dislocations. Dynamical processes, internal stress changes and the development of internal fields generally can be described by a redistribution of dislocations. In particular the spreading of dislocations can reveal mutual interactions between stress fields and consecutive changes of the internal stress concentrations. Applications to the following problems are briefly presented. 1. (1) The problem of deformation field on the earth's surface caused by the movement of dislocations is presented. Special attention is paid to the effects due to different slip directions and different motion directions. The direction of motion refers to an increment of dislocation surface. 2. (2) The problem of dislocation propagation in block structure is summarized. The mutual interaction of dislocations is discussed under the assumed structure conditions. Special attention is paid to the problem of crack initiation. The process called here “dislocations → crack” is discussed and some applications to the case of inclusions of a fluid phase are presented. The problem of volcanic earthquakes is considered in this way.