DIRECTIONS OF TECTONIC STRESS AND SOLUTIONS OF EARTHQUAKE SOURCE MECHANISMS

The relations between the radiation pattern of seismic waves, focal mechanism solution and the directions of the tectonic stress are investigated with the aid of the results of two-dimensional model experiments. The radiation pattern of seismic waves is dependent on the form of motion of the medium around the focus at the time of earthquake which is connected not only with the pre-existing stress before earthquake but also with other factors such as the geological conditions within the focal region. Based on the experimental results of rock mechanics as well as the results of our experiments, it can be assumed that the direction of the principal compres-sive tectonic stress is closer to the fault plane than the direction of principal com-pressive stress of release deduced from the focal mechanism solution.