Hierarchical block model for earthquakes.

The presented model for earthquakes is based on two fundamental principles: the hierarchical structure of seismic areas and the concept of self-organized criticality. The model reproduces the basic empirical properties of seismic processes: the frequency-energy scaling relation (the Gutenberg-Richter law), the generalized Omori law for temporal decay of aftershocks, the aftershock productivity law, the fractal distributions of hypocenters (epicenters) with power-law dependencies of the number of events on distances between hypocenters (epicenters), and, finally, the γ distribution for waiting times. In the model, the threshold energies depend on the block sizes and are distributed according to the Gauss law.

Force distribution in a granular medium under dynamic loading.

Force distribution in a granular medium subjected to an impulse loading is investigated in experiment and computer simulations. An experimental technique is developed to measure forces acting on individual grains at the bottom of the granular sample consisting of steel balls. Discrete element method simulation also is performed under conditions mimicking those in experiment.