We pursue accurate numerical techniques to obtain theoretical seismic waves for realistic three dimensional (3-D) Earth models using Spectral-Element Method. We have tried to solve forward problem, that is, to calculate synthetic seismic waveform for fully 3-D Earth model. We introduce a heterogeneous region at Earth's core-mantle boundary by combining a small, strongly anomalous region to a la...

Mantle control on planetary dynamos is often studied by imposing heterogeneous core-mantle boundary (CMB) heat flux patterns on the outer boundary of numerical dynamo simulations. These patterns typically enter two main categories: Either they are proportional to seismic tomography models of Earth’s lowermost mantle to simulate realistic conditions, or they are represented by single spherical h...

[1] Anomalous boundary layer structure at the core-mantle boundary (CMB) is investigated using a global set of broadband SKS and SPdKS waves from permanent and portable broadband seismometer arrays. SPdKS is an SKS wave that intersects the CMB at the critical angle for ScP, thus initiating a diffracted P wave (Pdiff) along the CMB at the core entry and exit locations. The waveshape and timing o...

The effect on composition and evoconvection with the entire mantle passing through lution of the mantle of the recently-observed the partial melt zone. Thus the lower mantle was strong concentration of iron in (Mg, Fe)O-magnedepleted of iron relative to both the upper siow•stite (row) at the expense of (Mg, Fe)SiO•mantle and the mantles of the small terrestrial perovskite (pv) structure is stud...

Oceanic lithosphere is rapidly recycled into the mantle through subduction, an important part of the dynamic evolution of the Earth. Cratonic continental lithosphere, however, can exist for billions of years, moving coherently with the tectonic plates. At the Caribbean–South American Plate margin, a complex subduction system and continental transform fault is adjacent to the South American crat...

The Earth’s magnetic field is measured on and above the crust, while turbulent dynamo in outer core produces values at core–mantle boundary (CMB). connection between two sets of usually assumed to be independent electrical conductivity mantle. However, magnetofluid a time-varying that must induce currents lower mantle as it emerges, since observed electrically conductive. Here, we develop model...

Extreme variations of Earth's magnetic field occurred in the Levant region around 1000 BC, when the field intensity rapidly rose and fell by a factor of 2. No coherent link currently exists between this intensity spike and the global field produced by the core geodynamo. Here we show that the Levantine spike must span >60° longitude at Earth's surface if it originates from the core-mantle bound...

(1) Introduction.-In this paper, the values of variables at the base of the mantle and top of the core in the Earth models to be considered will be indicated by the subscripts 1 and 2, respectively; k and p will denote the incompressibility and density; let Ak = k2ki and Ap = p2 pi. In an earlier Earth model,1 Model A, k1 = 6.5 X 1012 dyn/cm2 and k2 = 6.2 X 1012 dyn/cm2, giving Ak = -0.3 X 1012...

Recent results suggest that an iron-rich oxide may have fractionally crystallized from a primordial magma ocean and settled on the core–mantle boundary (CMB). Based on experimental results, the presence of only a few percent of Fe-rich oxide could slow seismic waves down by several percent. This heavy layer can become highly undulating as predicted from dynamic modeling but can remain as a sear...

The partial collapse of topographic structure at the core-mantle boundary (CMB) in avalanches, slumps or turbidity flows, would cause sudden temperature changes in both the upper core and the lower mantle. Although such collapses are hypothetical, it is interesting to investigate the potential consequences. Downwelling from such events could disrupt core convection cells and trigger geomagnetic...