SEISMOLOGICAL DETECTION OF A MANTLE PLUME

A detailed seismological study of the mantle beneath the Bowie hotspot, west of Canada, reveals a zone of low seismic velocities. The anomaly, probed at a depth of approximately 700 km, adds a delay of 0.15 s to the travel times of seismic waves traversing a region approximately 150 km In diameter, located approximately 150 km away from the vertical projection of the Bowie seamount. This observation suggests that a mantle plume is present in the lower mantle beneath Bowie, with the amplitude of the anomaly implying a temperature contrast of about approximately 300 K.