Full-wave tomographic imaging highlights small-scale mantle convection at the eastern North American margin

Plate edge-driven mantle upwelling and small-scale convection along the eastern margin of North America has shallowed the geotherm resulting in reduced seismic wave speeds and a weakened mantle lithosphere. Here we report results of a tomographic study using a finite-frequency sensitivity method and surface and body wave data to image the seismic wave speeds within eastern North America. Surface wave data, Rayleigh wave empirical Green's functions, are derived from up to 20 years of ambient noise, while body waves are from teleseismic earthquakes. Using solely surface waves data and a 3D strain-Green-tensor-based, scattering-integral method to compute sensitivity kernels, after 3 iterations we image large, low wave speed anomalies along the margin bounded by the continental and oceanic lithospheres. Our resolution with surface wave data is excellent greater than 3 degrees and good down to 1 degree with a loss of amplitude. Preliminary body-wave, travel-time residuals indicate similar features to the surface wave models including the southern and eastern edges of the craton and the prominent low wave speed anomalies along the margin. Following successful inversions of the teleseismic body wave data with sensitivity kernels from a 1D model, kernels will then be computed and updated using the full-wave method to reflect 3D wave speeds. Computation of full-wave, 3D sensitivity kernels will allow combining the surface and body wave data sets into a single model.