ON DETERMINING FOCAL MECHANISMS OF EARTHQUAKES IN THE MEDITERRANEAN REGION USING GRAPHIC METHOD

Purpose. The purpose of this paper is to show the effectiveness of the graphic method to solve the problem of determining the focal mechanisms of earthquakes and also to define the impact of the velocity model on the problem solution with a small number of stations. The obtained results were compared with the known focal mechanisms of these earthquakes. Design/methodology/approach. To determine the focal mechanism of earthquakes, the graphic method based on the polarity of the first arrival of P-waves was applied, as well as the information on fuzzy arrivals of P-waves and the S/P- wave amplitude ratio. Findings. The focal mechanism parameters of the two earthquakes in the Mediterranean Sea have been obtained. By determining one of the focal mechanisms, we demonstrated the impact of the velocity model on the important parameter necessary build up the focal mechanism by using graphic method ? the take off angle. Practical value/implications. The paper proves the effectiveness of the graphic method to determine the focal mechanisms since the results obtained by the graphic method and other methods are close we have demonstrated. The importance of the information on fuzzy arrivals of direct P waves at stations closely correlated as well as the choice of a velocity model. The development of the graphic method and its modifications may be applied to determine the focal mechanisms of earthquakes in the Carpathian region.