The S-wave project for focal mechanism studies, earthquakes of 1963

Abstract P- and S-wave data for thirty-five earthquakes selected from among the larger earthquakes of 1963 have been investigated. Focal mechanism determinations for twenty-six of these shocks are here presented. The solutions are based upon a combination of a graphical and a computer method for determining the poles of the nodal planes. In all cases it has been found that the mechanism may be adequately represented by a double couple as an equivalent point source of the focus, although in some few instances a single couple cannot be excluded as a possible alternate interpretation. The solution of a mid-Atlantic earthquake of November 17, 1963 is presented as an example of a focus which clearly conforms to the double couple model. Special attention is called to the solutions for a series of earthquakes in the Kurile Islands, and to three earthquakes of the mid-Atlantic.