Journal ArticleDOI
Complex Shear Wave Velocity Structure Imaged Beneath Africa and Iceland.
TLDR
A model of three-dimensional shear wave velocity variations in the mantle reveals a tilted low velocity anomaly extending from the core-mantle boundary region beneath the southeastern Atlantic Ocean into the upper mantle beneath eastern Africa, suggesting that Cenozoic flood basalt volcanism in the Afar region and active rifting beneath the East African Rift is linked to an extensive thermal anomaly at the CMB.Abstract:
A model of three-dimensional shear wave velocity variations in the mantle reveals a tilted low velocity anomaly extending from the core-mantle boundary (CMB) region beneath the southeastern Atlantic Ocean into the upper mantle beneath eastern Africa. This anomaly suggests that Cenozoic flood basalt volcanism in the Afar region and active rifting beneath the East African Rift is linked to an extensive thermal anomaly at the CMB more than 45 degrees away. In contrast, a low velocity anomaly beneath Iceland is confined to the upper mantle.read more
Citations
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Finite-Frequency Tomography Reveals a Variety of Plumes in the Mantle
TL;DR: In this article, the authors present tomographic evidence for the existence of deep-mantle thermal convection plumes, including six well-resolved plumes that extend into the lowermost mantle: Ascension, Azores, Canary, Easter, Samoa and Tahiti.
Journal ArticleDOI
Three distinct types of hotspots in the Earth's mantle
TL;DR: The origin of mantle hotspots is a controversial topic as mentioned in this paper, and only seven (primary) out of 49 hotspots meet criteria aimed at detecting a very deep origin (three in the Pacific, four in the Indo-Atlantic hemisphere).
Journal ArticleDOI
S40RTS: A degree-40 shear-velocity model for the mantle from new Rayleigh wave dispersion, teleseismic traveltime and normal-mode splitting function measurements
TL;DR: In this paper, a new collection of Rayleigh wave phase velocity, teleseismic body-wave traveltime and normal-mode splitting function measurements are used for modeling shear-velocity variation in Earth's mantle.
Journal ArticleDOI
Noble Gas Isotope Geochemistry of Mid-Ocean Ridge and Ocean Island Basalts: Characterization of Mantle Source Reservoirs
TL;DR: In the terrestrial environment, the abundances of noble gases are quite low because they were excluded from solid materials during planetary formation in the inner solar system, which makes the noble gases excellent tracers of mantle reservoirs as mentioned in this paper.
Journal ArticleDOI
Rupture Process of the 2004 Sumatra-Andaman Earthquake
Charles J. Ammon,Chen Ji,Hong-Kie Thio,David Robinson,Sidao Ni,Sidao Ni,Vala Hjörleifsdóttir,Hiroo Kanamori,Thorne Lay,Shamita Das,Donald V. Helmberger,Gene A. Ichinose,Jascha Polet,David J. Wald +13 more
TL;DR: The 26 December 2004 Sumatra-Andaman earthquake initiated slowly, with small slip and a slow rupture speed for the first 40 to 60 seconds, then the rupture expanded at a speed of about 2.5 kilometers per second toward the north northwest, extending 1200 to 1300 kilometers along the Andaman trough as discussed by the authors.
References
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Journal ArticleDOI
Preliminary reference earth model
TL;DR: In this paper, a large data set consisting of about 1000 normal mode periods, 500 summary travel time observations, 100 normal mode Q values, mass and moment of inertia have been inverted to obtain the radial distribution of elastic properties, Q values and density in the Earth's interior.
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Determination of earthquake source parameters from waveform data for studies of global and regional seismicity
TL;DR: In this article, an initial moment tensor is derived using one of the variations of the method described in detail by Gilbert and Dziewonski (1975), where perturbations to the elements of the moments are found simultaneously with changes in the hypocentral parameters.
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Convection Plumes in the Lower Mantle
TL;DR: The concept of crustal plate motion over mantle hotspots has been advanced to explain the origin of the Hawaiian and other island chains and the origin the Walvis, Iceland-Farroe and other aseismic ridges as discussed by the authors.
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The Resolving Power of Gross Earth Data
George E. Backus,Freeman Gilbert +1 more
TL;DR: In this article, the authors show how to determine whether a given finite set of gross Earth data can be used to specify an Earth structure uniquely except for fine-scale detail, and the shortest length scale which the given data can resolve at any particular depth.
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Mapping the upper mantle: Three‐dimensional modeling of earth structure by inversion of seismic waveforms
TL;DR: In this paper, the authors presented a method for the inversion of waveform data for the three-dimensional distribution of seismic wave velocities, applied to data from the global digital networks (International Deployment of Accelerometers, Global Digital Seismograph Network).