The possible reflection of mantle discontinuities in Pacific Geoid and bathymetry

Geoid anomalies over the Pacific plate show lineated undulations approximately oriented in the direction of absolute plate motion. Conventional spectral analyses have revealed a broad range of dominant wavelengths, but as filtering is direction-dependent, results are difficult to interpret. Here, we present a new approach designed to quantify the correlation between the geoid undulations and Pacific plate motion. We calculate the spatial correlation between geoid lineations and arbitrarily oriented, axisymmetric sinusoidal undulations of given wavelength. The pole (i.e., the orientation) of the sinuscid which maximizes the correlation is determined. The distance between this pole and the Pacific hotspot pole is calculated and represents a measure of how well a geoid lineation of a given wavelength aligns with Pacific plate motion. This distance varies with undulation wavelength and has discrete minima for several wavebands. These minima, moreover, occur at wavelengths whose values are remarkably close to the depths of seismically inferred mantle discontinuities. A similar analysis of available bathymetry corroborates these findings. If these correlations are significant, hey suggest that geoid (and bathymetry) undulations are influenced by mantle structure and thus are likely to reflect mantle dynamics.