Massive lithospheric thinning occurred in eastern China and large‐scale magmatism in South China occurred in the Mesozoic. Some geodynamic models have been proposed to explain their mechanisms, but are not consistent with each other. We apply anisotropic tomography to 32,728 P‐wave travel time data of 479 teleseismic events recorded at 225 stations to study the 3‐D anisotropic Vp structure of the upper mantle beneath central‐east China. P‐wave radial anisotropy is investigated for the first time in the study region. Our results show that an obvious low‐velocity zone exists in the asthenosphere under the eastern part of our study region, which represents upwelling thermal flow from the Cathaysia block to the North China block (NCB) according to the results of azimuthal and radial anisotropies. A distinct high‐velocity zone with weak radial anisotropy exists under the middle Yangtze block, which is explained as the stable cratonic root. Two other weak high‐velocity zones appear near or within the mantle transition zone under the middle‐lower Yangtze River and the eastern NCB, which might be detached lithosphere or the stagnant Pacific slab. Combining with previous geological and geochemical results, we consider that both the NCB and the South China block have undergone a common geodynamic process in the Mesozoic due to their similar age trending of igneous rocks, which could be explained by a flat‐slab subduction model and a ridge subduction model. These two models are associated with the paleo‐Pacific plate subduction that might have played a key role in the evolution of eastern China.

Precise geomagnetic navigation of aircraft without GPS can be challenging. However, the low accuracy of traditional magnetic data and the limitations of the existing geomagnetic matching algorithms affect its implementation. We propose a set of strategies to address these issues. First, we designed a towed airborne three-axis magnetic gradient device for measurements, which effectively reduced the influence of geomagnetic diurnal variation, geomagnetic storms, and aircraft interference. Second, we introduced a least-squares correction algorithm to enhance the accuracy of the magnetic data by reducing the heading error resulting from the magnetometer sensor. The algorithm improved the internal coincidence total accuracy (ICTA) from 0.6529 to 0.0186 nT, a remarkable 35-fold increase. Finally, we established a geomagnetic matching navigation algorithm called aeromagnetic gradient iterative closest contour point (AGICCP) for a three-axis gradient field, which corrected the cumulative error of the inertial navigation system (INS) in long-distance navigation. Our simulation experiments demonstrated that AGICCP outperforms the traditional ICCP and vector ICCP (VICCP) algorithms, reducing the position error from 736.96 and 174.70 m, respectively, to 26.73 m. The suggested magnetic gradient device and the proposed algorithms significantly improve the accuracy of geomagnetic navigation. This study provides new insights into precise airborne navigation with great practical significance.

We apply seismic tomography to 590,213 P‐wave arrival‐time data of 23,486 local earthquakes and 300,051 relative travel‐time residuals of 27,492 teleseismic events to study the 3‐D velocity structure of the crust and upper mantle beneath the entire Philippine Sea Plate (PSP) and its adjacent areas. Our results reveal significant high‐velocity anomalies beneath the Philippine Trench, the Japan‐Izu‐Bonin‐Mariana Trench, and the Nankai Trough, which reflect the subducted Philippine Sea slab, the Pacific slab, and the Shikoku Basin, respectively. On the basis of the tomographic images, we construct morphological models of these slabs. The slab morphologies become complex from the east to west. Taking into account previous results of geochemistry, paleomagnetism and numerical simulations, we deem that the complicated morphologies of the subducted slabs are related to the slab age, subduction rate, collision between different plates, clockwise rotation of the PSP, and retreat rate of trenches.