Mantle Shear-Wave Velocity Structure Beneath the Hawaiian Hot Spot

REPORTS-1.0 -0.7 -0.3 0.0 0.3 0.7 1.0-1.0 -0.7 -0.3 0.0 0.3 0.7 1.0A B Cdepth = 600 kmS-wave % velocity anomalydepth = 900 kmS-wave % velocity anomalydepth = 1200 km-1.0 -0.7 -0.3 0.0 0.3 0.7 1.0S-wave % velocity anomaly12121214141416161618 20 22 24Latitude18 20 22 24Latitude18 20 22 24Latitude262626282828303030168 166 164 162 160 158 156 154 152 150 148 146 144 142Longitude West(24), where steep lateral velocity gradients havebeen observed at the edges of the Pacific largelow-shear-velocity province (26).Our results improve the fidelity of S-wavemantle imaging around Hawaii as compared withprevious efforts and suggest that the upper mantlebeneath the islands is characterized by lowseismic velocities and, by inference, anomalouslyhigh temperatures. The peak-to-peak 3% velocityvariations that we imaged at 300 km depthin inversions with station terms corresponds to atemperature variation across the model of 250°C,and the 1.5% contrast near 900 km depth correspondsto a temperature variation of 300°C(24). These values are consistent with prior petrologicand geodynamic inferences of a hightemperatureplume beneath the Hawaiian hotspot (4–6, 10, 27).In terms of plume dynamics, the broad, lowvelocityanomaly at shallow mantle depths (