scholarly journals Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

2009 ◽  
Vol 30 (4-5) ◽  
pp. 407-461 ◽  
Author(s):  
Maureen D. Long ◽  
Paul G. Silver
Keyword(s):  
Shear Wave ◽  
Shear Wave Splitting ◽  
Wave Splitting ◽  
New Directions ◽  
Mantle Anisotropy

scholarly journals Insight into NE Tibetan Plateau expansion from crustal and upper mantle anisotropy revealed by shear-wave splitting

2017 ◽  
Vol 478 ◽  
pp. 66-75 ◽  
Author(s):  
Zhouchuan Huang ◽  
Frederik Tilmann ◽  
Mingjie Xu ◽  
Liangshu Wang ◽  
Zhifeng Ding ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Shear Wave ◽  
Upper Mantle ◽  
Shear Wave Splitting ◽  
Upper Mantle Anisotropy ◽  
Wave Splitting ◽  
Mantle Anisotropy ◽  
Insight Into ◽  
Ne Tibetan Plateau

scholarly journals Crustal seismic anisotropy of the Northeastern Tibetan Plateau and the adjacent areas from shear-wave splitting measurements

2019 ◽  
Vol 220 (3) ◽  
pp. 1491-1503 ◽  
Author(s):  
Nan Hu ◽  
Yonghua Li ◽  
Liangxin Xu
Keyword(s):  
Tibetan Plateau ◽  
Shear Wave ◽  
Seismic Anisotropy ◽  
Active Faults ◽  
Shear Wave Splitting ◽  
Crustal Anisotropy ◽  
Western Qinling ◽  
Northeastern Tibetan Plateau ◽  
Wave Splitting ◽  
Mantle Anisotropy

SUMMARY The Northeastern Tibetan Plateau has thickened crust and is still undergoing strong active crustal shortening and deformation. Crustal anisotropy can provide clues to how the crust is currently deforming and evolving. We use an automatic method to analyse the upper-crustal anisotropy of the NE Tibetan Plateau and the adjacent region using local earthquakes recorded at 39 permanent seismic stations during the period 2009–2018. The majority of the dominant fast directions are consistent with the maximum horizontal stress orientation, suggesting that the upper-crustal anisotropy is mainly controlled by the regional or local stress field. Several fault-parallel measurements are observed for stations on or near to the main faults. These fault-parallel fast directions indicate that the main mechanism of upper-crustal anisotropy is associated with shear fabric caused by deformation. Fast directions neither fault-parallel nor stress-parallel are observed at stations lying several kilometres away from fault zones, likely reflecting the combined influence of stress-aligned microcracks and active faults. A comparison between our upper-crustal anisotropy parameters and those inferred from previous anisotropy studies that used receiver function and teleseismic shear wave splitting measurements suggests that the crust has the same deformation mechanisms as mantle anisotropy in the southern part of the Western Qinling Fault, whereas the upper-crustal anisotropic mechanism is different from those of lower crust and mantle anisotropy in the northern part of the Western Qinling Fault. These observations imply that the Western Qinling Fault may be an important boundary fault.

Upper mantle anisotropy beneath North China from shear wave splitting measurements

2012 ◽  
Vol 522-523 ◽  
pp. 235-242 ◽  
Author(s):  
Lijun Chang ◽  
Chun-Yong Wang ◽  
Zhifeng Ding
Keyword(s):  
Shear Wave ◽  
Upper Mantle ◽  
North China ◽  
Shear Wave Splitting ◽  
Upper Mantle Anisotropy ◽  
Wave Splitting ◽  
Mantle Anisotropy

Upper mantle anisotropy beneath Sudetes from shear wave splitting - passive seismic experiment AniMaLS

2020 ◽  
Author(s):  
Julia Rewers ◽  
Piotr Środa ◽  
AniMaLS Working Group
Keyword(s):  
Shear Wave ◽  
Bohemian Massif ◽  
Upper Mantle ◽  
Shear Wave Splitting ◽  
Upper Mantle Anisotropy ◽  
Seismic Experiment ◽  
Wave Splitting ◽  
Passive Seismic ◽  
Mantle Anisotropy ◽  
Passive Seismic Experiment

<p>The passive seismic experiment AniMaLS was organized in 2017 in the Sudetes in Poland. One of the objectives was to study the anisotropy of the sub-crustal lithosphere and asthenosphere beneath the NE termination of the Bohemian Massif. Temporary seismic network of 23 broadband stations was operating in the area of Sudetes mountains and Fore-Sudetic Block, covering a ~200 x 100 km large area, with ~30 km spacing between stations. Obtained recordings were supplemented with data from permanent stations of Czech and Polish seismological networks located in the study area.</p><p>The Sudetes belong to internal zone of Variscan Orogen and are located in the NE part of the Bohemian Massif, between the Elbe Fault in SW and the Odra Fault in NE. The sudetic lithosphere represents a complex mosaic of several units with distinct histories of tectonic evolution and with consolidation ages ranging from the upper Proterozoic to the Quaternary. The aim of the project is to study seismic structure and anisotropy of the lithosphere-asthenosphere system based on broadband seismograms of local, regional and teleseismic events. The obtained data will be analysed using several interpretation methods. The poster presents the results of analysis by shear wave splitting method.</p><p>The analysis was done based on SKS and SKKS phases recorded during a ~2 years observation period. For analysis, three single-station methods were used: cross-correlation, eigenvalue minimization and transverse energy minimization. The dependence of resulting splitting parameters on the backazimuth of the event was also analysed. The results show that time delays between slow and fast S-wave components are typically in the range of ~0.5-1.6 sec, with average 1.2 sec. The splitting is interpreted as a result of lattice-preferred orientation (LPO) of mantle olivine. The azimuths of fast velocity axis are mostly consistent and showed largely WNW-ESE direction. They correlate well with trends of tectonic units observed at the surface and with strike directions of major fault zones. This suggests vertically coherent deformation throughout the lithosphere and frozen-in LPO, reflecting last tectonic episode which shaped Sudetic area. Obtained results were also compared with previous seismic studies of the upper mantle anisotropy in the neighboring areas by various methods.</p>

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