Spreading segments of the Mid-Atlantic Ridge show negative bull's-eye anomalies in the mantle Bouguer gravity field. Seismic refraction results from 33 degrees S indicate that these anomalies can be accounted for by variations in crustal thickness along a segment. The crust is thicker in the center and thinner at the end of the spreading segment, and these changes are attributable to variations...

RAYLEIGH waves from the Solomon Islands earthquake of July 29, 1950, recorded at Honolulu, Berkeley, Tucson, and Palisades are analyzed. Both the direct waves and those propagated through the Antipodes were observed for all stations except Honolulu. Application of a correction for land travel results in a dispersion curve for the oceanic portion of the path. It is found that the observed disper...

Abstract Reflection and critically refracted seismic methods use traveltime measurements of body waves propagating between a source series receivers on the ground surface to calculate subsurface velocities. Body wave energy is or reflected at boundaries where there change in impedance, defined as product material density velocity. This article provides practical guidance horizontally shear (SH-...