Seismic waves converted from velocity gradient anomalies in the Earth’s upper mantle

Anticorrelated seismic velocity anomalies from post-perovskite in the lowermost mantle.

Earth's lowermost mantle has thermal, chemical, and mineralogical complexities that require precise seismological characterization. Stacking, migration, and modeling of over 10,000 P and S waves that traverse the deep mantle under the Cocos plate resolve structures above the core-mantle boundary. A small -0.07 +/- 0.15% decrease of P wave velocity (Vp) is accompanied by a 1.5 +/- 0.5% increase ...

determination of velocity of seismic waves and upper crustal velocity model in shiraz seismological network

iran is located between two lithospheric plates (euroasia, arabian) and these two plates converge toward each other with a velocity of 25 mm/yr rate. shortening that produced from this convergence with makran subductin shows faulting and folding in zagros orogenic belt, alborz and kopedagh in north and sliding in sum strike slip faults with north-south trend in central iran. the nw-se trending ...

Shear - Velocity Heterogeneities in the Upper Mantle

Long-period surface waves are used to map lateral heterogeneities of velocity and anisotropy in the upper mantle. The dispersion curves are expanded in spherical harmonics up to degree 6 and inverted to find the depth structure. The data are corrected for the effect of surface layers and both Love and Rayleigh waves are used. Shear wave velocity and shear polarization anisotropy can be resolved...

Scanning for Velocity Anomalies in the Crust and Mantle with Diffractions from the Core-Mantle Boundary

Material for : “ Continent - sized low seismic velocity anomalies at the base of Earth ’ s mantle ”

In this paper, we discuss large low velocity provinces (LLVPs) in Earth’s lowermost mantle, explore their dynamics and possible composition, and consider evolutionary scenarios. The question of thermochemical piles as the origin to LLVPs is important, as it forms the foundation for our understanding of the thermal state of the mantle, the thermal and chemical evolution of Earth’s interior, the ...