Rockne H. Johnson

Contour Charts of SOFAR Speed and Axis Depth in the Pacific Ocean

Sound speeds, calculated from the physical properties of sea water as measured at hydrographic stations, were used to construct contour charts of SOFAR‐speed and SOFAR‐axis depth for the Pacific Ocean. Wilsons formula was used for the calculation of speed. Data were averaged for 1° squares, plotted, and smooth contours were drawn manually. Speeds averaged along great‐circle paths are compared with those measured for explosions. The charts show steep gradients along the Antarctic convergence and at the convergence of the Oyashio and Kuroshio extension. The region of highest speed, as well as greatest axis depth, was that extending eastward from Australia to about the 150°W. The charts are used in a program for calculating source coordinates of earthquake T phases.