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  • 1
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    Three-dimensional seismic models of the Earth's mantle (1995)
    In:  Rev. Geophys., Tokyo, Lawrence Livermore National Laboratory, vol. 33, no. 5, pp. 1-66, pp. L18610, (ISSN: 1340-4202)
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    Publication Date: 1995
    Keywords: Seismology ; Velocity depth profile ; Review article
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    BIBLIOGRAPHY SEISMOLOGY
  • 2
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    Eurasian surface wave tomography: Group velocities (1998)
    In:  J. Geophys. Res., Tokyo, Lawrence Livermore National Laboratory, vol. 103, no. B3, pp. 4839-4878, pp. L18610, (ISSN: 1340-4202)
    Details
    Publication Date: 1998
    Keywords: Surface waves ; Tomography ; Group veloc. ; 7255 ; Seismology ; Surface ; waves ; and ; free ; oscillations ; 7218 ; Lithosphere ; and ; upper ; mantle ; 7205 ; Continental ; crust ; (1242) ; 8180 ; Tectonophysics ; Tomography ; Europe ; Asia ; JGR
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    BIBLIOGRAPHY SEISMOLOGY
  • 3
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    Thinning and flow of Tibetan crust constrained by seismic anisotropy (2004)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 2004-07-13
    Description: Intermediate-period Rayleigh and Love waves propagating across Tibet indicate marked radial anisotropy within the middle-to-lower crust, consistent with a thinning of the middle crust by about 30%. The anisotropy is largest in the western part of the plateau, where moment tensors of earthquakes indicate active crustal thinning. The preferred orientation of mica crystals resulting from the crustal thinning can account for the observed anisotropy. The middle-to-lower crust of Tibet appears to have thinned more than the upper crust, consistent with deformation of a mechanically weak layer that flows as if confined to a channel.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shapiro, Nikolai M -- Ritzwoller, Michael H -- Molnar, Peter -- Levin, Vadim -- New York, N.Y. -- Science. 2004 Jul 9;305(5681):233-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Imaging the Earth's Interior, Department of Physics, University of Colorado at Boulder, Boulder, CO 80309, USA. nshapiro@ciei.colorado.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15247475" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    High-resolution surface-wave tomography from ambient seismic noise (2005)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 2005-03-12
    Description: Cross-correlation of 1 month of ambient seismic noise recorded at USArray stations in California yields hundreds of short-period surface-wave group-speed measurements on interstation paths. We used these measurements to construct tomographic images of the principal geological units of California, with low-speed anomalies corresponding to the main sedimentary basins and high-speed anomalies corresponding to the igneous cores of the major mountain ranges. This method can improve the resolution and fidelity of crustal images obtained from surface-wave analyses.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shapiro, Nikolai M -- Campillo, Michel -- Stehly, Laurent -- Ritzwoller, Michael H -- New York, N.Y. -- Science. 2005 Mar 11;307(5715):1615-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Imaging the Earth's Interior, Department of Physics, University of Colorado at Boulder, Boulder, CO, USA. nshapiro@ciei.colorado.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15761151" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
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    Seismic evidence for widespread western-US deep-crustal deformation caused by extension (2010)
    Nature Publishing Group (NPG)
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    Publication Date: 2010-04-09
    Description: Laboratory experiments have established that many of the materials comprising the Earth are strongly anisotropic in terms of seismic-wave speeds. Observations of azimuthal and radial anisotropy in the upper mantle are attributed to the lattice-preferred orientation of olivine caused by the shear strains associated with deformation, and provide some of the most direct evidence for deformation and flow within the Earth's interior. Although observations of crustal radial anisotropy would improve our understanding of crustal deformation and flow patterns resulting from tectonic processes, large-scale observations have been limited to regions of particularly thick crust. Here we show that observations from ambient noise tomography in the western United States reveal strong deep (middle to lower)-crustal radial anisotropy that is confined mainly to the geological provinces that have undergone significant extension during the Cenozoic Era (since approximately 65 Myr ago). The coincidence of crustal radial anisotropy with the extensional provinces of the western United States suggests that the radial anisotropy results from the lattice-preferred orientation of anisotropic crustal minerals caused by extensional deformation. These observations also provide support for the hypothesis that the deep crust within these regions has undergone widespread and relatively uniform strain in response to crustal thinning and extension.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Moschetti, M P -- Ritzwoller, M H -- Lin, F -- Yang, Y -- England -- Nature. 2010 Apr 8;464(7290):885-9. doi: 10.1038/nature08951.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Imaging the Earth's Interior, Department of Physics, University of Colorado at Boulder, Campus Box 390, Boulder, Colorado 80309, USA. mmoschetti@usgs.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20376148" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 6
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    Lithospheric structure of the Canadian Shield inferred from inversion of surface-wave dispersion with thermodynamic a priori constraints (2007)
    In:  Geological Society Special Publication 239: 175-194.
    Details
    Publication Date: 2007-10-08
    Description: We argue for and present a reformulation of the seismic surface-wave inverse problem in terms of a thermal model of the upper mantle and apply the method to estimate lithospheric structure across much of the Canadian Shield. The reformulation is based on a steady-state temperature model, which we show to be justified for the studied region. The inverse problem is cast in terms of three thermal parameters: temperature in the uppermost mantle directly beneath Moho, mantle temperature gradient, and the potential temperature of the sublithospheric convecting mantle. In addition to the steady-state constraint, prior physical information on these model parameters is based on surface heat flow and heat production measurements, the condition that melting temperatures were not reached in the crust in Proterozoic times and other theoretical considerations. We present the results of a Monte Carlo inversion of surface-wave data with this thermal parameterization' subject to the physical constraints for upper mantle shear velocity and temperature, from which we also estimate lithospheric thickness and mantle heat flux. The Monte Carlo inversion gives an ensemble of models that fit the data, providing estimates of uncertainties in model parameters. We also estimate the effect of uncertainties in the interconversion between temperature and seismic velocity. Variations in lithospheric temperature and shear velocity are not well correlated with geological province or surface tectonic history. Mantle heat flow and lithospheric thickness are anti-correlated and vary across the studied region, from 11 mW/m2 and nearly 400 km in the northwest to about 24 mW/m2 and less than 150km in the southeast. The relation between lithospheric thickness and mantle heat flow is consistent with a power law relation similar to that proposed by Jaupart et al. (1998), who argued that the lithosphere and asthenosphere beneath the Canadian Shield are in thermal equilibrium and heat flux into the deep lithosphere is governed by small-scale sublithospheric convection.
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  • 7
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    A seismic reference model for the crust and uppermost mantle beneath China from surface wave dispersion (2016)
    Oxford University Press
    Details
    Publication Date: 2016-06-13
    Description: Using data from more than 2000 seismic stations from multiple networks arrayed throughout China (CEArray, China Array, NECESS, PASSCAL, GSN) and surrounding regions (Korean Seismic Network, F-Net, KNET), we perform ambient noise Rayleigh wave tomography across the entire region and earthquake tomography across parts of South China and Northeast China. We produce isotropic Rayleigh wave group and phase speed maps with uncertainty estimates from 8 to 50 s period across the entire region of study, and extend them to 70 s period where earthquake tomography is performed. Maps of azimuthal anisotropy are estimated simultaneously to minimize anisotropic bias in the isotropic maps, but are not discussed here. The 3D model is produced using a Bayesian Monte Carlo formalism covering all of China, extending eastwards through the Korean Peninsula, into the marginal seas, to Japan. We define the final model as the mean and standard deviation of the posterior distribution at each location on a 0.5° x 0.5° grid from the surface to 150 km depth. Surface wave dispersion data do not strongly constrain internal interfaces, but shear wave speeds between the discontinuities in the crystalline crust and uppermost mantle are well determined. We design the resulting model as a reference model, which is intended to be useful to other researchers as a starting model, to predict seismic wave fields and observables and to predict other types of data (e.g. topography, gravity). The model and the data on which it is based are available for download. In addition, the model displays a great variety and considerable richness of geological and tectonic features in the crust and in the uppermost mantle deserving of further focus and continued interpretation.
    Keywords: Seismology
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 8
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    Seismic evidence for lithospheric modification associated with intracontinental volcanism in Northeastern China (2015)
    Oxford University Press
    Details
    Publication Date: 2015-11-20
    Description: Using data predominantly from the NECESS Array, but also incorporating surface wave data from surrounding networks, we present the results of a Bayesian Monte Carlo inversion of receiver functions, Rayleigh wave ellipticity (H/V ratio) and Rayleigh wave group and phase speeds from 8 to 80 s period for the 3-D shear velocity structure of the crust and uppermost mantle beneath Northeast China. We define the final model as the mean and standard deviation of the posterior distribution at each location on a 0.5° x 0.5° grid from the surface to 150 km depth. The primary scientific motivation is to investigate the expression of intracontinental volcanism across the region. The model lithosphere displays prominent features (middle and lower crustal velocity, Moho depth, lithospheric thickness) across the study area that coincide with the location of volcanoes, which are predominantly situated in two distinct volcanic regions, which we call the ‘Northeast China Lineated Quaternary Volcanic Zone’, found near the eastern margin of the Songliao Basin and extending to Changbaishan Volcano, and the ‘Northern and Southern Greater Xing'an Range Pleistocene Volcanic Zones’. There is a strong similarity between the lateral distribution of depth-integrated mantle velocity anomalies in our model with the teleseismic body wave model of Tang et al ., although the vertical distribution of anomalies differ.
    Keywords: Seismology
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 9
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    Inferring the oriented elastic tensor from surface wave observations: preliminary application across the western United States (2015)
    Oxford University Press
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    Publication Date: 2015-03-26
    Description: Radial and azimuthal anisotropy in seismic wave speeds have long been observed using surface waves and are believed to be controlled by deformation within the Earth's crust and uppermost mantle. Although radial and azimuthal anisotropy reflect important aspects of anisotropic media, few studies have tried to interpret them jointly. We describe a method of inversion that interprets simultaneous observations of radial and azimuthal anisotropy under the assumption of a hexagonally symmetric elastic tensor with a tilted symmetry axis defined by dip and strike angles. We show that observations of radial anisotropy and the 2 component of azimuthal anisotropy for Rayleigh waves obtained using USArray data in the western United States can be fit well under this assumption. Our inferences occur within the framework of a Bayesian Monte Carlo inversion, which yields a posterior distribution that reflects both variances of and covariances between all model variables, and divide into theoretical and observational results. Principal theoretical results include the following: (1) There are two distinct groups of models (Group 1, Group 2) in the posterior distribution in which the strike angle of anisotropy in the crust (defined by the intersection of the foliation plane with Earth's surface) is approximately orthogonal between the two sets. (2) The Rayleigh wave fast axis directions are orthogonal to the strike angle in the geologically preferred group of models in which anisotropy is strongly non-elliptical. (3) The estimated dip angle may be interpreted in two ways: as a measure of the actual dip of the foliation of anisotropic material within the crust, or as a proxy for another non-geometric variable, most likely a measure of the deviation from hexagonal symmetry of the medium. The principal observational results include the following: (1) Inherent S -wave anisotropy ( ) is fairly homogeneous vertically across the crust, on average, and spatially across the western United States. (2) Averaging over the region of study and in depth, in the crust is approximately 4.1 ± 2 per cent. in the crust is approximately the same in the two groups of models. (3) Dip angles in the two groups of models show similar spatial variability and display geological coherence. (4) Tilting the symmetry axis of an anisotropic medium produces apparent radial and apparent azimuthal anisotropies that are both smaller in amplitude than the inherent anisotropy of the medium, which means that most previous studies have probably underestimated the strength of anisotropy.
    Keywords: Seismology
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 10
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    Joint inversion of surface wave dispersion and receiver functions: a Bayesian Monte-Carlo approach (2013)
    Oxford University Press
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    Publication Date: 2013-01-11
    Description: A non-linear Bayesian Monte-Carlo method is presented to estimate a Vsv model beneath stations by jointly interpreting Rayleigh wave dispersion and receiver functions and associated uncertainties. The method is designed for automated application to large arrays of broad-band seismometers. As a testbed for the method, 185 stations from the USArray Transportable Array are used in the Intermountain West, a region that is geologically diverse and structurally complex. Ambient noise and earthquake tomography are updated by applying eikonal and Helmholtz tomography, respectively, to construct Rayleigh wave dispersion maps from 8 to 80 s across the study region with attendant uncertainty estimates. A method referred to as ‘harmonic stripping method’ is described and applied as a basis for quality control and to generate backazimuth independent receiver functions for a horizontally layered, isotropic effective medium with uncertainty estimates for each station. A smooth parametrization between (as well as above and below) discontinuities at the base of the sediments and crust suffices to fit most features of both data types jointly across most of the study region. The effect of introducing receiver functions to surface wave dispersion data is quantified through improvements in the posterior marginal distribution of model variables. Assimilation of receiver functions quantitatively improves the accuracy of estimates of Moho depth, improves the determination of the Vsv contrast across Moho, and improves uppermost mantle structure because of the ability to relax a priori constraints. The method presented here is robust and can be applied systematically to construct a 3-D model of the crust and uppermost mantle across the large networks of seismometers that are developing globally, but also provides a framework for further refinements in the method.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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