SKS splitting beneath Capital area of China

Chang, Ling; Wang, Chunyong; Ding, Zhongli

doi:10.1007/s11589-008-0553-1

Cited by 10 publications

(12 citation statements)

References 14 publications

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“…According to Table 2, the average fast shear-wave polarization of SKS through the upper mantle is obtained at NE 110.17° in this study. This differs from the NE 108.92° reported elsewhere [29,30] by only 1.25°. However, the average fast shearwave polarization of crustal direct shear-wave is NE 95.15°, 15.02° different with that of the fast SKS polarization obtained in this study.…”

Section: Characteristics Of Crust-mantle Seismic Anisotropy In North contrasting

confidence: 80%

“…In this region, SKS splitting results at BJT were obtained first by the Vinnik method [12]. Later, with more data, a study using the SC method obtained parameters of SKS splitting at BJT with results that are fully consistent with the Vinnik method [14] and also consistent with other independent studies [13,29,30]. The SC method has now been widely adopted globally to calculate SKS splitting.…”

Section: Methodssupporting

confidence: 59%

“…One reported fast polarization of NE 59°±5° at BJT [43] contrasts with others. However, the fast polarization calculated by the different Vinnik method [12] is in harmony with several others [13,14,29] that use the same SC method. Furthermore, the results in this paper calculated from 46 high-quality data for records spanning 10 years, make it believable that the fast SKS polarization is at NE 104.5°±22.1°.…”

Section: Characteristics Of Crust-mantle Seismic Anisotropy In North mentioning

confidence: 70%

“…There are two main crust-mantle deformation models, Sim- Polarization of fast SKS phases extracted from Chang et al [29,30] 108. ple Asthenospheric Flow (SAF) [48] and Vertical Coherent Deformation (VCD) [49], both of which are based on the hypothesis of driving-plate force. On the basis of SKS splitting information and surface GPS measurements, Wang et al [16] inferred that crust-mantle deformation within the Tibetan Plateau agrees with the strong coupling VCD crustmantle model.…”

Section: Discussion Of Seismic Anisotropy In North China and Crust-mamentioning

confidence: 99%

“…Furthermore, we obtain average polarizations of fast shear-waves by station averaging in three different data sets (Table 2). In North China, Chang et al [29,30] measured SKS splitting from CASN stations and also from stations of the temporary North China Seismic Array, deployed by the Institute of Geophysics, China Earthquake Administration. Figure 1 displays the results of fast shear wave polarizations of SKS splitting at the 62 stations in this area; average results are listed in Table 2.…”

Section: Characteristics Of Crust-mantle Seismic Anisotropy In North mentioning

confidence: 99%

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Crust-mantle coupling in North China: Preliminary analysis from seismic anisotropy

Gao

2010

Chin. Sci. Bull.

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Seismology) are compared with data from a temporary North China Seismic Array to obtain the background orientation of the horizontal crustal principal compressive stress at NE 95.1°±15.4° in North China. Data are corrected for disturbances of faults and irregular tectonics, and are used to constrain the fast SKS polarization at NE 110.2°±15.8° in North China. Individual station analyses suggests that there is consistently more than 10° difference between the polarizations of fast shear-wave in the crust and those of fast SKS phases. Azimuthally anisotropic phase velocities of Rayleigh waves at different periods also indicate an orientation change for fast velocity with depth. It suggests the crust-mantle coupling in North China follows neither the simple decoupling model nor the strong coupling model. Instead, it is possibly some inhomogeneous combination of two models or some gradual-change model of physical characteristics. This study shows that anisotropy in the crust and mantle could be multiply characterized more correctly and crust-mantle coupling could be analyzed further, if increasing near-field shear-wave splitting data that indicate crustal anisotropy, combined with the azimuthal anisotropy of Rayleigh waves, besides the result of SKS splitting travelling through lithosphere and surface GPS measurements. seismic anisotropy, crust-mantle coupling, polarization direction of fast shear-wave, shear-wave splitting, crustal principal compressive stress, North China Citation:Gao Y, Wu J, Yi G X, et al. Crust-mantle coupling in North China: Preliminary analysis from seismic anisotropy.

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Section: Characteristics Of Crust-mantle Seismic Anisotropy In North contrasting

confidence: 80%

Section: Methodssupporting

confidence: 59%

Section: Characteristics Of Crust-mantle Seismic Anisotropy In North mentioning

confidence: 70%

Section: Discussion Of Seismic Anisotropy In North China and Crust-mamentioning

confidence: 99%

Section: Characteristics Of Crust-mantle Seismic Anisotropy In North mentioning

confidence: 99%

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Crust-mantle coupling in North China: Preliminary analysis from seismic anisotropy

Gao

2010

Chin. Sci. Bull.

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Tele‐Seismic PS‐Wave Splitting from the Basement in the Capital Area of China

Chen

2014

Chinese J of Geophysics

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An important advantage of tele-seismic PS-waves is carrying the anisotropy information of media beneath seismic stations. This paper uses the analysis method of three-component PS-wave splitting to analyze the basement PS-waves based on the high-precision tele-seismic data of Capital Area Seismic Network (CASN) from 2002 to 2003. The purpose is to acquire the PS-wave splitting parameters beneath the seismic stations, including polarization of fast PS-waves and the time delays of fast and slow PS-waves, and to reveal the shallow crust anisotropy beneath the seismic stations. The results show that this method preserves the original information of the wave field, which allows us to analyze the features of PS-wave splitting. The tele-seismic PS-waves from the basement recorded by short period stations have the advantage of less noise and higher SNR, and have splitting phenomena commonly. Besides we find the time delay of fast and slow PS-waves is beyond our expectation, which has average values of time delay 0.1∼0.2 s. This research can be compared with shear-wave splitting, which would help recognize anisotropy and stress state of crust and study tectonics and seismic activity. et al. 2008a. Inversion of the upper crustal velocity structure in capital area with Pg wave. . 2005. Three dimensional P wave velocity tomography and deep structure related to strong earthquake in Capital area. Chinese Sci. Bull. (in Chinese), 50(4): 348-355.

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Upper mantle anisotropy in the Ordos Block and its margins

Chang

Wang

Ding

2011

Sci. China Earth Sci.

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Based on the polarization analysis of teleseismic data, SKS (SKKS) fast-wave directions and delay times between fast and slow shear waves were determined for each of the 111 seismic stations from both permanent and temporary broadband seismograph networks deployed in the Ordos Block and its margins. Both the Silver and Chan and stacking analysis methods were used. In this way, an image of upper mantle anisotropy in the Ordos Block and its margins was acquired. In the western and northern margins of the Ordos Block, the fast-wave directions are consistently NW-SE. The fast-wave directions are mainly NWW-SEE and EW in the southern margin of the Ordos Block. In the eastern margin of the Ordos Block, the fast-wave directions are generally EW, although some run NEE-SWW or NWW-SEE. In the Ordos Block, the fast-wave directions trend near N-S in the north, but switch to near EW in the south. The delay time between fast and slow waves falls into the interval 0.48-1.50 s, and the average delay time at the stations in the Ordos Block is less than that in its margins. We suggest that the anisotropy of the stable Ordos Block is mainly caused by "fossil" anisotropy frozen in the ancient North China Craton. The NE-trending push of the northeastern margin of the Tibetan Plateau has caused NW-SE-trending lithospheric extension in the western and northern margins of the Ordos Block, and made the upper mantle flow southeastwards. This in turn has resulted in the alignment of the upper mantle peridotite lattice with the direction of material deformation. In the southern margin of the Ordos Block, the collision between the North China and Yangtze blocks resulted in the fast-wave direction running parallel to the collision boundary and the Qinling Orogen. Combining this with the APM and velocity structure of the Qinling Orogen, we propose that eastward-directed asthenospheric-mantle channel flow may have occurred beneath the Qinling Orogen. In the eastern margin of the Ordos Block, the complex anisotropic characteristics of the Fenhe Graben and Taihang Orogen may be caused by the interaction of western Pacific Plate subduction, regional extensional tectonics, and the orogeny. For station YCI, the apparent splitting parameters (the fast-wave directions range from 45° to 106° and the delay times range from 0.6 to 1.5 s) exhibit systematic variations as a function of incoming polarization with a periodicity of /2. This variation can be best explained by a two-layer anisotropic model ( lower = 132°, t lower = 0.8 s,  upper = 83°, t upper = 0.5 s). The upper layer anisotropy beneath station YCI can again be attributed to "fossil" anisotropy frozen in the ancient North China Craton. The lower layer anisotropy is affected by the tectonic activity of the western Ordos Block. The NW-SE trending extension caused by the NE trending push of the northeastern margin of the Tibetan Plateau affected the deformation of the lower anisotropic layer beneath station YCI. By comparing the fast-wave directions with GPS velocity directions, we see that ...

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SKS splitting beneath Capital area of China

Cited by 10 publications

References 14 publications

Crust-mantle coupling in North China: Preliminary analysis from seismic anisotropy

Crust-mantle coupling in North China: Preliminary analysis from seismic anisotropy

Tele‐Seismic PS‐Wave Splitting from the Basement in the Capital Area of China

Upper mantle anisotropy in the Ordos Block and its margins

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