scholarly journals The influence of plate motions on three-dimensional back arc mantle flow and shear wave splitting

2000 ◽  
Vol 105 (B12) ◽  
pp. 28009-28033 ◽  
Author(s):  
Chad E. Hall ◽  
Karen M. Fischer ◽  
E. M. Parmentier ◽  
Donna K. Blackman
2006 ◽  
Vol 244 (3-4) ◽  
pp. 566-575 ◽  
Author(s):  
T. Volti ◽  
A. Gorbatov ◽  
H. Shiobara ◽  
H. Sugioka ◽  
K. Mochizuki ◽  
...  

2003 ◽  
Vol 30 (12) ◽  
Author(s):  
Rengin Gök ◽  
James F. Ni ◽  
Michael West ◽  
Eric Sandvol ◽  
David Wilson ◽  
...  

Author(s):  
Enbo Fan ◽  
Yumei He ◽  
Yinshuang Ai ◽  
Stephen S. Gao ◽  
Kelly H. Liu ◽  
...  

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4988
Author(s):  
Nico De Marchi ◽  
WaiChing Sun ◽  
Valentina Salomoni

The triggering and spreading of volumetric waves in soils, namely pressure (P) and shear (S) waves, developing from a point source of a dynamic load, are analyzed. Wave polarization and shear wave splitting are innovatively reproduced via a three-dimensional Finite Element research code upgraded to account for fast dynamic regimes in fully saturated porous media. The mathematical–numerical model adopts a u-v-p formulation enhanced by introducing Taylor–Hood mixed finite elements and the stability features of the solution are considered by analyzing different implemented time integration strategies. Particularly, the phenomena have been studied and reconstructed by numerically generating different types of medium anisotropy accounting for (i) an anisotropic solid skeleton, (ii) an anisotropic permeability tensor, and (iii) a Biot’s effective stress coefficient tensor. Additionally, deviatoric-volumetric coupling effects have been emphasized by specifically modifying the structural anisotropy. A series of analyses are conducted to validate the model and prove the effectiveness of the results, from the directionality of polarized vibrations, the anisotropy-induced splitting, up to the spreading of surface waves.


2020 ◽  
Author(s):  
Eric Löberich ◽  
Götz Bokelmann

<p>The association of seismic anisotropy and deformation, as e.g. exploited by shear-wave splitting measurements, provides a unique opportunity to map the orientation of geodynamic processes in the upper mantle and to constraint their nature. However, due to the limited depth-resolution of steeply arriving core-phases, used for shear-wave splitting investigations, it appears difficult to differentiate between asthenospheric and lithospheric origins of observed seismic anisotropy. To change that, we take advantage of the different backazimuthal variations of fast orientation <em>φ</em> and delay time <em>Δt</em>, when considering the non-vertical incidence of phases passing through an olivine block with vertical b-axis as opposed to one with vertical c-axis. Both these alignments can occur depending on the type of deformation, e.g. a sub-horizontal foliation orientation in the case of a simple asthenospheric flow and a sub-vertical foliation when considering vertically-coherent deformation in the lithosphere. In this study we investigate the cause of seismic anisotropy in the Central Alps. Combining high-quality manual shear-wave splitting measurements of three datasets leads to a dense station coverage. Fast orientations <em>φ</em> show a spatially coherent and relatively simple mountain-chain-parallel pattern, likely related to a single-layer case of upper mantle anisotropy. Considering the measurements of the whole study area together, our non-vertical-ray shear-wave splitting procedure points towards a b-up olivine situation and thus favors an asthenospheric anisotropy source, with a horizontal flow plane of deformation. We also test the influence of position relative to the European slab, distinguishing a northern and southern subarea based on vertically-integrated travel times through a tomographic model. Differences in the statistical distribution of splitting parameters <em>φ</em> and <em>Δt</em>, and in the backazimuthal variation of <em>δφ</em> and <em>δΔt</em>, become apparent. While the observed seismic anisotropy in the northern subarea shows indications of asthenospheric flow, likely a depth-dependent plane Couette-Poiseuille flow around the Alps, the origin in the southern subarea remains more difficult to determine and may also contain effects from the slab itself.</p>


2017 ◽  
Vol 44 (13) ◽  
pp. 6735-6742 ◽  
Author(s):  
Colton Lynner ◽  
Megan L. Anderson ◽  
Daniel E. Portner ◽  
Susan L. Beck ◽  
Hersh Gilbert

2009 ◽  
Vol 288 (3-4) ◽  
pp. 359-369 ◽  
Author(s):  
Maureen D. Long ◽  
Haiying Gao ◽  
Amanda Klaus ◽  
Lara S. Wagner ◽  
Matthew J. Fouch ◽  
...  

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