[1] Tharsis province is a major center of Martian volcanic activity characterized by large gravity and topography anomalies. The origin of Tharsis is debated. One hypothesis is that the province was produced by melting associated with a mantle plume from the coremantle boundary. An alternative hypothesis is that Tharsis formed by a plume associated with an impact. Recent studies have shown that...

The purpose of this note is to demonstrate that recent VP and V, profiles are consistent with finite strain extrapolations of reasonable mineralogies. The difference in the size of the discontinuities in the Vp and V, profiles is due to the relative pressure insensitivity of shear velocity in spin el structures. Most of the structure in the upper mantle can be attributed to the collapse of fors...

A persistent reversal in the expected polarity of the initiation of vertically polarized shear waves that graze the D'' layer (the layer at the boundary between the outer core and the lower mantle of Earth) in some regions starts at the arrival time of horizontally polarized shear waves. Full waveform modeling of the split shear waves for paths beneath the Caribbean requires azimuthal anisotrop...

The internal structure of the continental lithosphere holds the key to its creation and development, and this internal structure can be determined using appropriate seismic and electromagnetic methods. These two are complementary in that the seismic parameters usually represent bulk properties of the rock, whereas electrical conductivity is primarily a function of the connectivity of a minor co...

[1] Between 105–115 degrees, the SKS waveform is complicated by the formation of SPdKS, a wave that has segments of P diffraction along the core mantle boundary. While previous studies have primarily focused on the moveout of SPdKS from SKS, we analyze the concomitant reduction of the SKS amplitude. Long-period SKKS/SKS amplitude ratios present a coherent global pattern. SKKS/ SKS is relatively...

[1] Vertical crustal motions at 15 sites along the northern Pacific-North America plate boundary are determined using relative sea level changes from tide gauge records. Our analysis is based on monthly mean sea levels, from which barometric pressure and seasonal effects are removed. The records are corrected for common-mode oceanographic variations. These records are statistically examined for...

We present models of mantle convection focused on the situation in early Mars in which particular attention is paid to water and its effects on partial melting, melt extraction, and viscosity. We have combined the mantle convection program STAGYY [7] with a parameterized thermodynamic model of martian mantle mineralogy [5] and carried out calculations of convection in a twodimensional compressi...

[1] The double-crossing hypothesis posits that postperovskite bearing rock in Earth’s D00 layer exists as a layer above the core-mantle boundary bounded above and below by intersections between a curved thermal boundary layer geotherm and a relatively steep phase boundary. Increasing seismic evidence for the existence of pairs of discontinuities predicted to occur at the top and bottom of this ...

[1] Models of convection in the mantle can be used to study the effects of differentiation and remixing on the geochemical evolution of the Earth. Implementation of melting and degassing at mid-ocean ridges and subduction zones requires an adequate approximation of plate tectonics as well as temperature-dependent rheology. We have developed a new two-dimensional cylindrical model that combines ...

[1] A dynamic link between the early evolution of Tharsis and the crustal dichotomy on Mars was recently proposed by Zhong (2009). We address in detail the fundamental aspects of the proposed model using 3‐D spherical shell modeling of convection. We investigate the conditions under which a spherical harmonic degree 1 flow is produced in the mantle of Mars in layered viscosity models with diffe...