Imaging mantle discontinuities and velocity structures using the Radon transform

Transition zone discontinuities highlight density and velocity variations in the mantle and provide key information on the Earth's thermal and chemical evolution. SS precursors are highly sensitive to upper mantle discontinuities and have been used to image large-scale mantle structures. Traditional methods to increase the signal-to-noise ratio in SS precursors are stacking or slowness slant stack, which cannot well constrain the ray parameter. To overcome the limitation of these methods, the Radon transform is introduced to suppress background noise, simultaneously constrain differential travel times and ray parameters, and detect weak reflected or converted phases.; By applying Radon transforms, we are able to delineate discontinuity structures beneath the northeastern Pacific Ocean and the northwest Canada. Also, differential travel time curves or ray parameters impose alternative constraints on the upper-lower mantle velocity structure beneath hotspot locations, in addition to the depth of 400-km discontinuity and transition zone thickness.