AFTERSHOCKS AS INDICATORS OF THE STATE OF STRESS IN A FAULT SYSTEM

Abstract

The deviation of aftershocks number decreasing in time from the exponential low (Omori low) in the aftershocks series start can be correlated with the aftershock zone's stress state characteristics. The analysis of a large number of aftershock series generated by medium-strength earthquakes in some seismic zone allows quantitative estimation of the average stress and strength difference in this zone. It is shown that before strong earthquakes the smooth increase of this parameter is observed, and after them - fast and substantial decrease.