Effect of vibrations on the laboratory model "earthquake" statistics

Earthquakes result from the development of a dynamic instability of the stick-slip type in a system of faults in the Earth's crust, when the elastic energy accumulated during a long smooth motion of fragments exhibits rapid relaxation when the stresses reach a critical level. The statistics of dynamic instabilities has been studied in a model tribological system demonstrating an analogous behavior. A distribution function of the magnitude of acceleration, which arises upon slippage of a sample modeling a fragment of the Earth's crust, covers several orders of magnitude. This is analogous to the statistics of real earthquakes obeying the Gutenberg-Richter law. The possibility of modifying the model "earthquake" statistics by means of an external vibrational action upon the system has been studied: the external action was controlled so as to decrease the probability of strong (high-acceleration) jumps at the expense of weak jumps, thus converting the displacement dynamics into a creep regime. It is established that the "earthquake" statistics in most of the tribological couples studied can be modified in a desired manner under the action of vibrations.