In view of the problems that traditional pseudo-range phase combination method and STPIR method are greatly affected by observation noise and multi-path effect under low sampling rate, cycle slip is easily misjudged under strong noise environment, and detection performance is affected during periods of frequent or drastic changes in ionospheric activity. We introduce the time window method to improve the judgment conditions of pseudo-range phase combination method and STPIR method considering altitude angle, and the weighted recursive smoothing method is combined with time window to improve the algorithm. Experimental verification is conducted using observation data of IGS stations. The results show that the improved algorithm can detect and repair various types of cycle slips well.

We numerically simulate the error characteristics and global static gravity field detection performance of cold atom interference (CAI) gradiometer, electrostatic gradiometers (EA, MicroSTAR, GOCE), and their combined satellite gravity gradiometers (CAI-EA, CAI-MicroSTAR) in the nadir-pointing mode, and deeply analyze the gravity gradient observation noise contributed by accelerometers and angular velocity of satellite rotation at the design level. Based on the simulated gradient observations of near-polar satellite orbits at 200 km and 250 km altitude for 90 d, we analyze the ability of different types of gradiometers and different noise levels in static gravity field inversion. The results show that CAI can significantly reduce low-frequency noise levels. The performance of combined gradiometers in gravity field inversion is better than EA, MicroSTAR and GOCE, considering the nominal noise of electrostatic gradiometers and the different noise levels of CAI, and CAI whose noise approximates white noise is better than electrostatic gradiometers in low degree. When the orbit altitude is 200 km and the accuracy of CAI accelerometers is 3.5×10^-12 m/(s²·$\sqrt{\mathrm{Hz}} $), the cumulative geoid errors of CAI-EA, CAI-MicroSTAR and GOCE gradiometers are 2.9 cm, 3.2 cm and 3.7 cm at the degree of 300, and the highest degrees which the cumulative geoid error is 1 cm are 250, 240 and 225, respectively.

Aiming at the problems that approximate solution accuracy of the existing coordinate mean method is insufficient, and the conversion relationship between image coordinate system and tangent plane coordinate system of celestial sphere cannot be applied to large field of view, we develop an algorithm model for precise calculation of astronomical coordinates of rotation axis of zenith camera with ultra-large field of view. Based on the shafting deviation between the main optical axis and rotation axis, we construct a spherical triangle pointing to the north celestial pole and the two shafting systems, and construct a precise solution model of astronomical coordinates pointing to rotation axis based on spherical coordinates. The simulation results show that when the latitude coordinate pointed by the main optical axis is less than 80°, the calculation error of latitude coordinate is less than 1″, the calculation error of azimuth angle is less than 5″ and the calculation error of height angle is less than 0.4″, the calculation error of astronomical coordinate pointed by rotation axis is less than 1″.

Aimed at the lunar environment characterized by high vacuum, low gravity, and minimal seismic activity, a three-axis lunar surface gravimeter based on electrostatic accelerometer technology is proposed. The working principle, performance specifications, and application scenarios of the gravimeter are presented. Theoretical results and simulation curves indicate that the gravimeter has a vertical measurement range of approximately 2.9 m/s², exceeding the lunar surface gravitational acceleration, with a resolution of about 82 μGal/Hz^1/2. In the horizontal direction, the range is about 0.12 m/s² with a resolution of approximately 4 μGal/Hz^1/2. Ultimately, this design enables high-precision gravity measurements on the Moon, offering a new payload solution for China's lunar gravity research and laying the groundwork for future lunar gravity exploration.

To further evaluate the technical performance of domestic independently developed absolute gravimeters, this study conducted comparison observations using multiple absolute gravimeters in the cave of the Huazhong University of Science and Technology National Gravimetry Laboratory. Through unified data processing, high-precision absolute gravity comparison data were obtained. The results demonstrate that no significant deviation exists between atomic interferometry absolute gravimeters and laser interferometry absolute gravimeters in this comparison, with deviations all within -4.95 μGal to 5.31 μGal. Each atomic interferometry absolute gravimeter achieved an observation precision of 1 μGal during continuous 4-hour measurements, with inter-instrument deviations maintained below 10 μGal, demonstrating excellent stability and consistency. This study marks the first comparison measurements conducted on multiple domestically developed absolute gravimeters featuring independent domestic. It involved detailed data processing, scientific evaluation, and a multidimensional performance assessment, providing crucial references for the subsequent development and application of domestic gravimeters.

Using Schuster statistical test method, the correlation between tidal body stress and moderate and small earthquakes occurred in the epicenter and its vicinity before the Xizang Dingri M_S6.8 earthquake on January 7, 2025 is investigated. The test results were evaluated by the statistical parameter P value, and the lower the P value, the stronger the statistical significance of the correlation. According to the phase angle statistics of the tidal force modulation caused by the semidiurnal tide and the semilunar tide in the epicenter, the P value of the semidiurnal tide test result is 1.26%, which is lower than triggering threshold of the tidal stress, and most earthquakes occur near the minimum of the semidiurnal tide; the P value of the semilunar tide does not pass the significance test. Further analysis of the temporal and spatial smoothing windows of the P-value based on the semidiurnal tide shows that the P-value decreases significantly before the Dingri M_S6.8 earthquake, and the low P-value area of the spatial smoothing window is concentrated in the north of the epicenter of the Dingri M_S6.8 earthquake. It is shown that the occurrence of moderate and small earthquakes in the epicenter and its vicinity before the Dingri M_S6.8 earthquake is obviously related to the triggering of solid tide, and these moderate and small earthquakes have certain precursory significance for the occurrence of the Dingri M_S6.8 earthquake.

Based on the continuous seismic ambient noise data from 48 stations in Wuhan-Ezhou-Huanggang-Huangshi (WEHH) metropolitan area and adjacent regions, we use ambient noise tomography method to obtain Rayleigh-wave phase velocity structure at periods of 5 s to 40 s. The results show that phase velocity structure of the upper to middle crust is closely correlated with regional tectonic units. The low-velocity anomalies are observed along the eastern margin of Jianghan basin and the southern margin of Dabie mountain, whereas the Dabie orogen is marked by high-velocity anomalies. In the middle to lower crust, the Moho topography influences the phase velocity structure, with a crust-penetrating low-velocity anomaly near the Wulongquan fault, suggesting a potential pathway for deep material upwelling. The Dabie orogen retains high-velocity anomalies associated with its metamorphic basement. At greater depths, from the lower crust to the uppermost mantle, widespread low-velocity anomalies are observed, which may be attributed to lithospheric delamination or mantle-derived material upwelling. The low-velocity anomalies on both sides of Yangtze river are closely linked to the formation of middle-lower Yangtze metallogenic belt, reflecting a spatiotemporal coupling between deep geodynamic processes and shallow mineralization. This study has higher resolution than previous imaging results, which can provide more reliable insights for revealing the deep geodynamic mechanisms of regional tectonic evolution and mineralization.

Based on the structural characteristics of the Xianshuihe fault zone, this study divides the five sections of Luhuo, Daofu, Qianning, Zheduotang, and Kangding-Moxi, and quantitatively reveals the horizontal slip rate and kinematic characteristics of each section through multi-source observation data of cross-fault leveling, baseline/ranging, and horizontal creep. The results show that the whole Xianshuihe fault zone is dominated by left-lateral strike-slip mode from 1982 to 2024. The strike-slip rates of Juwo and Xialatuo in Luhuo section are -0.9 mm/a and -2.86 mm/a, and the cumulative strike-slip displacements are 40 mm and 130 mm, which are significantly higher than the activity intensity of Gelu and Xuxu stations. The strike-slip rates of Goupu and Goupu creep stations in Daofu-Qianning section are -0.97 mm/a and -0.58 mm/a, and the cumulative displacement shows a linear growth trend. The horizontal displacement of Longdengba and Laoganning stations is small, and the local fault zone is weakly sinistral. The Zheduotang observation site in the Kangding-Moxi section shows a +0.2 mm/a dextral strike-slip, while the Yulin observation site maintains a stable left-lateral strike-slip of -0.12 mm/a, and its deformation has significant seasonal fluctuations (amplitude of about 1.5 mm to 2.3 mm). The cross-fault leveling of the Anshun site shows continuous tensile normal fault activity, and the linearity of the movement trend reaches 0.933 and 0.824, respectively.The results of segmented comparison show that the activity intensity of the northwestern section is significantly higher than that of the southeastern section, and the vertical movement shows that the thrust of the northern section and the normal fault activity of the southern section are structural inversion. The segmentation difference is related to the fault geometry and the physical properties of the medium. The medium strength of the conversion layer in the northwest section may be lower than that in the southeast section, which is easy to trigger slip and lead to shorter earthquake recurrence period. Combined with the regional stress field, it is found that the locking degree of the Xianshuihe fault zone has changed in different periods, showing that the fault in the northwest section is more active than that in the southeast section, and the locking is weak. At the same time, after the Wenchuan M_S8.0 earthquake, the Lushan M_S7.0 earthquake, and the Luding M_S6.9 earthquake, the extrusion rate of the Bayan Har block to the Sichuan basin accelerated, which affected the far-field left-lateral strike-slip rate of the Xianshuihe fault and the accumulation rate of fault slip deficit, which in turn led to the difference in the stress and strain accumulation rate of each segment on the Xianshuihe fault zone.

Multi-temporal InSAR, in combination with ascending and descending Sentinel-1A data, was applied to obtain two-dimensional surface deformation of the Alto Guadalentín basin from January 2020 to December 2022. The time series deformation, which was refined by independent component analysis (ICA), was then integrated with groundwater level data to estimate the aquifer parameters in the study area. The results showed that the main deformation center of the Alto Guadalentín basin was close to Lorca city in the north and the deformation mainly occurred in the vertical direction with the maximum deformation rate of -65 mm/a. Moreover, the Alto Guadalentín basin represented two different spatiotemporal deformation characteristics: long-term linear deformation and seasonal deformation. The skeleton storage coefficient of the aquifer in the study area ranged between 0.66×10^－2 and 2.93×10^－2, the average annual groundwater storage loss is －3.8×10⁷m³, which was consistent with the previous researches. The research results could provide reference data and information support for groundwater resource management and land subsidence control in the region.

The observed data show that the BM1-BM3 branch of the Dashuitou cross-fault in the Haiyuan fault zone exhibited a reverse faulting change of 1.52 mm in November 2023, and another sudden reverse faulting jump of 1.71 mm on March 6, 2024. To verify whether this anomaly is related to tectonic movement, we obtain the time series of surface deformation in the Dashuitou cross-fault site by InSAR technology. It analyzes the possible causes of the cross-fault deformation anomaly from the deformation field's spatial distribution and time evolution. The results show that: 1) The coal mining areas around the site have obvious subsidence, and the subsidence rate changes rapidly over time. The cumulative shape variable from January 2023 to June 2024 is about 23 cm, and the significant deformation range is about 1 km². 2) The benchmark points are significantly affected by mining-induced subsidence, exhibiting varying degrees of settlement over time. The closer they are to the mining area, the greater the subsidence magnitude and the faster the rate. 3) Comparing the results of InSAR and leveling observation, the trend and magnitude of cross-fault deformation in the same period are the same. In summary, the abnormal leveling deformation of the Dashuitou cross-fault site may be caused by the settlement of the mining area.