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Tauzin Benoit, Debayle Eric, Wittlinger Grard, . (2008). The mantle transition zone as seen by global Pds phases: No clear evidence for a thin transition zone beneath hotspots
. J. Geophys. Res., 113(B8), B08309–.
Keywords: P-to-S conversions, mantle transition zone, subduction hotspot plume, 7208 Seismology: Mantle, 7203 Seismology: Body waves, 7240 Seismology: Subduction zones, 8137 Tectonophysics: Hotspots, large igneous provinces, and flood basalt volcanism, 8147 Tectonophysics: Planetary interiors,
Programme: 133
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McLeod M.G. (1994). Magnetospheric and ionospheric signals in magnetic observatory monthly means: Electrical conductivity of the deep mantle. J. Geophys. Res., 99(b7), 13577–13590.
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Hu X G, Liu L T, Kroner C, Sun H P, . (2009). Observation of the seismic anisotropy effects on free oscillations below 4 mHz
. J. Geophys. Res., 114(B7), B07301–.
Abstract: We present observations of significant fundamental spheroidal-toroidal mode coupling at frequencies below 4 mHz in the early part of vertical component records from seismic stations on near-equatorial source-receiver propagation paths after the 26 December 2004 and 28 March 2005 great Sumatra earthquakes. Since the mixed-type coupling induced by rotational Coriolis force are very weak at these selected equatorial-path stations, we investigate what effects mimic the strong Coriolis effects at frequencies below 4 mHz, suggesting that local azimuthal anisotropy in the upper mantle is the most likely explanation for the strong anomalous coupling we observed. In addition, strong anisotropy coupling observed in the frequency band of 14 mHz is always characterized by anomalous small amplitudes of coupled spheroidal modes on the vertical component of seismograph, suggesting that excitation of quasi-toroidal modes by azimuthal anisotropy associates with geometric nodes of fundamental spheroidal modes.
Keywords: seismic anisotropy, free oscillations of the earth, mixed-type mode coupling, 7255 Surface waves and free oscillations, 7208 Mantle, 7299 General or miscellaneous,
Programme: 133
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La Chapelle S., Castelnau O., Lipenkov V.Y. & Duval P. (1998). Dynamic recrystallization and texture development in ice as revealed by the study of deep ice cores in Antarctica and Greenland. J. Geophys. Res., 103(b3), 5091–5105.
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Ohtaki Toshiki, Kaneshima Satoshi, Kanjo Kenji, . (2012). Seismic structure near the inner core boundary in the south polar region
. J. Geophys. Res., 117(B3), B03312–.
Keywords: P-wave velocity and attenuation, inner and outer core, south polar region, 1507 Core processes, 7203 Body waves, 7207 Core, 8115 Core processes, 8124 Earth's interior: composition and state,
Programme: 133
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Lagabrielle Y., Garel E., Dauteuil O. & Cormier M.H. (2001). Extensional faulting and caldera collapse in the axial region of fast spreading ridges: Analog modeling. J. Geophys. Res., 106(b2), 2005–2015.
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Nettles Meredith, Dziewoski Adam M, . (2008). Radially anisotropic shear velocity structure of the upper mantle globally and beneath North America
. J. Geophys. Res., 113(B2), B02303–.
Keywords: North America, seismic velocity, anisotropy, 7208 Seismology: Mantle, 7218 Seismology: Lithosphere, 7270 Seismology: Tomography, 7255 Seismology: Surface waves and free oscillations,
Programme: 133
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Gung Yuancheng, Hsu Ya-Ting, Chiao Ling-Yun, Obayashi Masayuki, . (2009). Multiscale waveform tomography with two-step model parameterization
. J. Geophys. Res., 114(B11), B11301–.
Abstract: In geophysical tomography, a proper model parameterization scheme for forward modeling is not necessarily a suitable one for the inversion stage, and vice versa. To take full advantage of the merits of parameterization in both stages, we propose a two-step model parameterization approach, in which different model bases for forward computation and inversion are adopted and the basis change is achieved by applying a spatial projection directly to the sensitivity matrix. We demonstrate this approach through an experimental study of waveform tomography for the Pacific upper mantle shear wave structure using first-orbit long-period Rayleigh waves. In the forward modeling, a normal-mode-based nonlinear asymptotic coupling theory is used for the computation of the synthetics and sensitivity matrix, and the model is parameterized in terms of spherical harmonics which provide efficient analytical solutions for path integrals in the forward modeling. Prior to the inversion, the model basis of the sensitivity matrix is transformed to local functions within the study region. After mapping, only local bases around the data sampling path receive effective sensitivities. Accordingly, the computation cost in the inversion is significantly reduced. Furthermore, the two-step model parameterization also adds flexibility to the inversion schemes. In particular, a wavelet-based multiscale inversion is implemented, and its results are compared to simple damping solutions. The general concept and applications of the two-step model parameterization are not restricted to the forwarding modeling technique or model parameterization schemes employed in this experimental study. This approach benefits any inverse problems wherever transformation of model bases helps to better constrain the results.
Keywords: multiscale tomography, two-step model parameterization, nonlinear asymptotic coupling theory, 3260 Mathematical Geophysics: Inverse theory, 7270 Seismology: Tomography, 7255 Seismology: Surface waves and free oscillations,
Programme: 133
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. (2009). Absolute plate motions constrained by shear wave splitting orientations with implications for hot spot motions and mantle flow
. J. Geophys. Res., 114(B10), B10405–.
Keywords: absolute plate motion, seismic anisotropy, mantle flow, hot spot, 8011 Kinematics of crustal and mantle deformation, 8158 Plate motions: present and recent, 8121 Dynamics: convection currents, and mantle plumes,
Programme: 133
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Camps P., Henry B., Prevot M. & Faynot L. (2001). Geomagnetic paleosecular variation recorded in Plio-Pleistocene volcanic rocks from Possession Island (Crozet Archipelago, southern Indian ocean). J. Geophys. Res., 106(b1), 1961–1971.
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