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The fast orientation and magnitude of crustal azimuthal anisotropy beneath the southeastern Tibetan Plateau and adjacent areas are measured by analyzing the sinusoidal moveout of the P to S converted phase from the Moho. Beneath the tectonically active plateau, the mean magnitude is 0.48 ± 0.13 s, which is about twice as large as that observed in the stable Sichuan Basin (0.23 ± 0.10 s). The two areas are separated by the Longmenshan fault zone, a zone of devastating earthquakes including the 12 May 2008 MW 7.9 Wenchuan earthquake. Fault orthogonal fast orientations observed in the southern Longmenshan fault zone, where previous studies have revealed high crustal Vp/Vs and suggested the presence of mid‐lower crustal flow, may reflect flow‐induced lattice preferred orientation of anisotropic minerals. Fault parallel anisotropy in the central segment of the fault zone is most likely related to fluid filled fractures, and fault perpendicular extensional cracks are probably responsible for the observed anisotropy in the northern segment. The crustal anisotropy measurements, when combined with results from previous studies, suggest the existence of mid‐lower crustal flow beneath the southeastern margin of the plateau. Comparison of crustal anisotropy obtained before and after the Wenchuan earthquake suggests that the earthquake has limited influence on whole crustal anisotropy, although temporal changes of anisotropy associated with the earthquake have been reported using splitting of shear waves from local earthquakes occurred in the upper crust.

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To characterize crustal anisotropy beneath the central North China Craton (CNCC), we apply a recently developed deconvolution approach to effectively remove near‐surface reverberations in the receiver functions recorded at 200 broadband seismic stations and subsequently determine the fast orientation and the magnitude of crustal azimuthal anisotropy by fitting the sinusoidal moveout of the P to S converted phases from the Moho and intracrustal discontinuities. The magnitude of crustal anisotropy is found to range from 0.06 s to 0.54 s, with an average of 0.25 ± 0.08 s. Fault‐parallel anisotropy in the seismically active Zhangjiakou‐Penglai Fault Zone is significant and could be related to fluid‐filled fractures. Historical strong earthquakes mainly occurred in the fault zone segments with significant crustal anisotropy, suggesting that the measured crustal anisotropy is closely related to the degree of crustal deformation. The observed spatial distribution of crustal anisotropy suggests that the northwestern terminus of the fault zone probably ends at about 114°E. Also observed is a sharp contrast in the fast orientations between the western and eastern Yanshan Uplifts separated by the North‐South Gravity Lineament. The NW‐SE trending anisotropy in the western Yanshan Uplift is attributable to “fossil” crustal anisotropy due to lithospheric extension of the CNCC, while extensional fluid‐saturated microcracks induced by regional compressive stress are responsible for the observed ENE‐WSW trending anisotropy in the eastern Yanshan Uplift. Comparison of crustal anisotropy measurements and previously determined upper mantle anisotropy implies that the degree of crust‐mantle coupling in the CNCC varies spatially.

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The Mufushan-Jiaoshan fault (MJF) is a hidden active fault located on the north side of the Ningzhen Mountain Range and developed along the Yangtze River in Zhenjiang area, China. In this paper, the structure of MJF is detected and studied using group-velocity ambient noise tomography. In the study area (18 km × 25 km), 47 short-period seismic stations were deployed with the average station spacing of about 3 km and 24 days (from 27 February to 22 March 2019) of continuous ambient-noise recordings were collected. And 510 group velocity dispersion curves in the period band 0.5–5 s were extracted using the vertical component data. And then the three-dimensional shear-wave velocity structure was inverted using group dispersion data by the direct surface-wave tomographic method. Our results are consistent with the geological background of the study area, showing that in the depth range of 0.6–1.5 km, the north side of MJF presents a relatively high velocity, and the south side presents a distribution pattern of high and low velocity. While in the depth range of 1.5–2.0 km, the shear-wave velocity (Vs) model is relatively simple with relatively low velocity on the north side and relatively high velocity on the south side. And the gradient zone of Vs may be the location of the main fracture surface of MJF. The good correspondence between the Vs model and the fault structure indicates that the ambient noise tomography method can be used as an effective method for detecting hidden faults in urban environments.

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Abstract. Star sensor is an important part of the attitude control of a space vehicle. At the time of image acquisition, CMOS sensors will have some fixed pattern noise which will affect the image capture effects. From the practical application, this article apply the average of de-noising algorithm to eliminate the effects of noise caused by fixed pattern, which can effectively improve the accuracy of image capture, thus helping centroid localization be more accurate.