SCSIO OpenIR  > 中科院边缘海地质重点实验室
Structure imaging of the crust and upper mantle in south of Alaska
Liu, CX; Wang, Z;
AbstractFor the first time we used 562891 P- and 156321 S-wave travel-time data to invert for the V-P and V-S structures simultaneously in the crust and upper mantle in south of Alaska. At the same time, the Poisson' s ratio images were calculated from the inverted velocity models. Our tomographic results provide crucial information for a better understanding of seismic structures and the geometry of the subducting slabs under south of Alaska. The P-wave velocity is similar to that of the S-wave velocity and coincides well with the Poisson's ratio image. Strong high velocity (V-P, V-S) and low Poisson's ratio (sigma) anomalies down to 200 km depth are clearly imaged along the Alaska subduction zone, indicating the subducting Pacific and Yakutat slabs. The high-velocity and low-sigma zone is well consistent with the spatial distribution of the earthquakes along the subducting slab. Most of large earthquakes (M>6. 5) are located in the boundaries between the high- and low-velocity zones, suggesting strong interplate coupling of the subducting slabs. Wide low-velocity anomalies with high Poisson's ratio are revealed in the mantle wedge of the subduction zone, which might reflect the magmatic flow associated with the slab subduction. Our study indicates the dipping angle of the slab changes from steep in the Wrangell Block to flat under the Bristol Bay in south of Alaska, which is associated with the Yakutat plate under the Wrangell Block and the Pacific plate subducting under the Bristol Bay. A strong low-velocity body in the upper mantle is observed under the conjunction of the Kenai Peninsula and the Kodiak Island, suggesting the collision of the Yakutat and Pacific plates as well as the strong upwelling of the mantle asthenosphere that might have thinned the subducting plate there.
Department[Liu Cun-Xi ; Wang Zhi] Chengdu Univ Technol, State Key Lab Oil & Gas Reservoir Geol & Exploita, Chengdu 610059, Peoples R China ; [Wang Zhi] Chinese Acad Sci, South China Sea Inst Oceanol, Key Lab Marginal Sea Geol, Guangzhou 510301, Guangdong, Peoples R China
KeywordPacific Slab Subduction Seismic Tomography Earthquake Generation Interplate Coupling Yakutat Plate
Subject AreaGeochemistry & Geophysics
Indexed Bysci
Funding Project海洋地质
WOS IDWOS:000339645100008
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Document Type期刊论文
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GB/T 7714
Liu, CX,Wang, Z, Structure imaging of the crust and upper mantle in south of Alaska[J]. CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION,2014,57(7):2113-2126.
APA Liu, CX,Wang, Z,& imaging of the crust and upper mantle in south of Alaska.CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION,57(7),2113-2126.
MLA Liu, CX,et al."Structure imaging of the crust and upper mantle in south of Alaska".CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION 57.7(2014):2113-2126.
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