a r t i c l e i n f o a b s t r a c t Isostatic and dynamic models of Earth's surface topography can provide important insights into the driving processes of tectonic deformation. We analyze these two estimates for the tectonically-active western United States using refined structural models derived from EarthScope USArray. For the crust, use of recent Moho depth measurements and crustal densit...

In this thesis we investigate the solidification of early magma oceans on the Earth and the formation of a deep dense layer at the core-mantle boundary. We also study the concentrations and densities of the last layers of the solidified magma ocean and how they create a deep dense layer after solid-state overturn. The deep dense layer that forms in our model matches the bulk physical properties...

S U M M A R Y This study applies high-resolution Radon transform to a large set of SS precursors and explores the mantle reflectivity structure beneath 17 potentially ‘deep-rooted’ hotspots. The combined reduced time (τ ) and ray parameter (p) information effectively constrains the depth, spatial distribution and sharpness of upper-/mid-mantle reflectors. The olivine to wadsleyite phase boundar...

[1] We investigate the effects of lateral viscosity variations (LVVs) on mantle circulation model predictions of the global geoid. The present study is motivated in part by earlier findings that LVVs due to stiff slabs in the lower mantle have a strong influence on the geoid, and that slabs in the lower mantle are perhaps no stronger than the ambient mantle. However, more recently, it has been ...

[1] Accurately inferring the radially anisotropic structure of the mantle using seismic waveforms requires correcting for the effects of crustal structure on waveforms. Recent studies have quantified the importance of accurate crustal corrections when mapping upper mantle structure using surface waves and overtones. Here, we explore the effects of crustal corrections on the retrieval of deep ma...

We report that a sharp lateral boundary exists at the southern edge of the Pacific superplume. The set of SHdiff waveforms, which graze the South Pacific, have similar features to those observed previously at the southeastern edge of the African superplume. Both waveform sets show a rapid shift of the arrival time and the broadening of the waveforms with respect to the azimuth as previously rep...

[1] Abstract: We predict plate motions from a comprehensive inversion of theoretical estimates of tectonic forces in order to evaluate the relative importance of these and the uncertainties of such models. Plate-driving forces from the mantle are calculated using global flow models that are driven by tomography and subduction-derived density fields. Observed and predicted plate velocities agree...

[1] We image the crustal architecture of the Musgrave Province with petrophysically constrained forward models of new potential field data. These models image divergent shallow-dipping crustal scale thrusts that, at depth, link with an axial zone defined by steeper, lithospheric scale transpressional shear zones. They also show that to permit a near-surface density distribution that is consiste...

Three-dimensional numerical simulations of convection and magnetic ®eld generation in the Earth’s core now span several hundred thousand years; the magnetic ®eld created during most of this time has an intensity, structure and time dependence similar to the present geomagnetic ®eld. Five models are described here. The ®rst is a homogeneous Boussinesq model, driven steadily by heat sources on th...