The slip in the dislocation plane produces blocking at an early stage and the uneasiness of slip at grain boundaries leads to high brittleness of the material after hot rolling.

With a continuously distributed dislocation model, this paper deals with cracks inclined to a free surface of a semi infinite plane under remote loadings.

The changes on static stress, acquired according to the half-space elastic dislocation theory, can exist on fault plane for a long time until the next strong earthquake.