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During the summer of 1966 a joint marine refraction survey was conducted across the Hawaiian arch by the Scripps Institution of Oceanography, the University of Hawaii, Oregon State University, and the University of Wisconsin. Conventional and unique types of refraction profiles were shot to study the directional dependence of velocity or velocity anisotropy of the mantle and the depth configuration of the Mohorovicic discontinuity. A two-dimensional delay time function method was used to study (1) the anisotropy and (2) the delay-time surface. The upper mantle was found to display compressional velocity anisotropy amounting to about 0.6 km/sec difference between the maximum and minimum velocities with the direction of maximum velocity being east-west. The delay time surface suggests t at, as expected from earlier work, the mantle is generally shallow along the crest of the arch. The shallowest region occurs near the southeast end of the arch, where it intersects the Molokai fracture zone. The mantle deepens southwest of the crest of the arch as the Hawaiian deep is approached.

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