Seismic Anisotropy Tomography and Mantle Dynamics

Zhao, Dapeng1; Liu, Xin2; Wang, Zewei3; Gou, Tao4

2023

10.1007/s10712-022-09764-7

SURVEYS IN GEOPHYSICS   Impact Factor & Quartile

0169-3298

1573-0956

Seismic anisotropy tomography is the updated geophysical imaging technology that can reveal 3-D variations of both structural heterogeneity and seismic anisotropy, providing unique constraints on geodynamic processes in the Earth's crust and mantle. Here we introduce recent advances in the theory and application of seismic anisotropy tomography, thanks to abundant and high-quality data sets recorded by dense seismic networks deployed in many regions in the past decades. Applications of the novel techniques led to new discoveries in the 3-D structure and dynamics of subduction zones and continental regions. The most significant findings are constraints on seismic anisotropy in the subducting slabs. Fast-velocity directions (FVDs) of azimuthal anisotropy in the slabs are generally trench-parallel, reflecting fossil lattice-preferred orientation of aligned anisotropic minerals and/or shape-preferred orientation due to transform faults produced at the mid-ocean ridge and intraslab hydrated faults formed at the outer-rise area near the oceanic trench. The slab deformation may play an important role in both mantle flow and intraslab fabric. Trench-parallel anisotropy in the forearc has been widely observed by shear-wave splitting measurements, which may result, at least partly, from the intraslab deformation due to outer-rise yielding of the incoming oceanic plate. In the mantle wedge beneath the volcanic front and back-arc areas, FVDs are trench-normal, reflecting subduction-driven corner flows. Trench-normal FVDs are also revealed in the subslab mantle, which may reflect asthenospheric shear deformation caused by the overlying slab subduction. Toroidal mantle flow is observed in and around a slab edge or slab window. Significant azimuthal and radial anisotropies occur in the big mantle wedge beneath East Asia, reflecting hot and wet upwelling flows as well as horizontal flows associated with deep subduction of the western Pacific plate and its stagnation in the mantle transition zone. The geodynamic processes in the big mantle wedge have caused craton destruction, back-arc spreading, and intraplate seismic and volcanic activities. Ductile flow in the middle-lower crust is clearly revealed as prominent seismic anisotropy beneath the Tibetan Plateau, which affects the generation of large crustal earthquakes and mountain buildings.

Seismic anisotropy Seismic tomography Subduction zones Earthquake Volcano

SCI

English

Others

Japan Society for the Promotion of Science[19H01996] ; Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan[THK-05] ; National Natural Science Foundation of China["41972211","4179046","41904045"]

Geochemistry & Geophysics

Geochemistry & Geophysics

WOS:000914246200001

SPRINGER

GEOSCIENCES

Web of Science

1.Tohoku Univ, Grad Sch Sci, Dept Geophys, Sendai 9808578, Japan
2.Ocean Univ China, Coll Marine Geosci, Qingdao 266100, Peoples R China
3.Southern Univ Sci & Technol, Dept Earth & Space Sci, Shenzhen 518055, Peoples R China
4.Chinese Acad Sci, South China Sea Inst Oceanol, Guangzhou 510301, Peoples R China

Zhao, Dapeng,Liu, Xin,Wang, Zewei,et al. Seismic Anisotropy Tomography and Mantle Dynamics[J]. SURVEYS IN GEOPHYSICS,2023.

Zhao, Dapeng,Liu, Xin,Wang, Zewei,&Gou, Tao.(2023).Seismic Anisotropy Tomography and Mantle Dynamics.SURVEYS IN GEOPHYSICS.

Zhao, Dapeng,et al."Seismic Anisotropy Tomography and Mantle Dynamics".SURVEYS IN GEOPHYSICS (2023).