Aiming the issue of reduced accuracy in sea surface height inversion using global navigation satellite system interferometric reflectometry (GNSS-IR) due to elevation angle deviation, a correction method for elevation angle deviation based on the ionospheric region is proposed. To verify the reliability of the correction method for elevation angle deviation, a comparison is made between the inversion results before and after applying the correction to the elevation angle deviation. The results indicate that the inversion results, after correction for elevation angle deviation, exhibit higher accuracy. The method for correcting elevation angle deviation can effectively rectify the deviation caused by the ionosphere.

Current robust fitting algorithms are prone to failure in point cloud data with a high contamination rate. To solve this problem, we introduce a weight matrix in the plane fitting method based on eigenvalue decomposition, where the initial weight is determined based on the normal vector information of point cloud, thus reducing the influence of outliers. We further use the scale-adaptive method to enhance the robustness. The scale factor of this method gradually decreases as the number of iterations increases, effectively solving the problem of low breakdown ration of traditional M estimation. The experimental results show that the breakdown ratio of the proposed algorithm is higher than that of existing robust point cloud fitting methods, and it can accurately estimate plane parameters in the point cloud data with a high outlier ratio.

To objectively evaluate the accuracy of TPXO series ocean tide models for the eastern China sea(ECS), we use the latest FES2014b and EOT20 as reference models. The assessment is performed by computing the root mean square error(RMSE) of the M₂ vertical ocean tide loading(OTL) displacements and the root sum square(RSS) of the 8 principal tidal constituents based on the GPS-observed M₂ vertical OTL displacements and tide gauge observations from the evenly selected 22 GPS sites and 65 tide gauges in the coastal areas, respectively. The results show that: 1) In the whole ECS, EOT20 is the most accurate model with RMSE of 0.41 mm and RSS of 11.1 cm, while the accuracy of FES2014b is slightly lower with RMSE of 0.43 mm and RSS of 11.4 cm. 2) Along the coast of eastern China and the western Korean Peninsula, there are large differences between TPXO models and FES2014b, and the RSS with tide gauge observations are 2-6 times as much as that of FES2014b and EOT20. 3) Both TPXO9_Atlas and TPXO8_Atlas agree better than other models with the M₂ vertical OTL observations in the Ryukyu Islands, and the two models are suggested for the local correction of OTL displacements.

Using the BIC_tp noise model identification criterion, we analyzed the temporal noise characteristics of sea surface height (SSH) and their influencing factors at 350 virtual coastal satellite altimetry stations worldwide. Furthermore, we explored the impact of environmental loads on SSH time series and the characteristics of sea level changes across different time spans. The results indicate that the assumptions of FN+WN, FN+RW+WN, and PL+WN noise models can lead to errors in estimating the velocity parameters of SSH time series. Furthermore, there is a diversity of SSH time series noise models, and the velocity uncertainties under different noise models vary significantly. Identifying their noise characteristics is crucial for accurately obtaining sea level change parameters. The average global sea level rise rates for the different time spans of 1993 to 2006, 2007 to 2020, and 1993 to 2020 are 2.59 mm/a, 4.41 mm/a, and 3.08 mm/a, respectively, indicating that sea level is accelerating its rise. The optimal noise models and velocity changes for the SSH time series before and after environmental loading correction are not significant, indicating that the load effect has a relatively minor impact on the characteristics of SSH time series.

We successfully estimate ice shelf thickness products for Antarctic ice shelves among 2003 and 2022 from the ICESat, CryoSat-2, and ICESat-2 altimetry satellites. The results reveal a rapid thinning trend in the Antarctic ice shelves overall. The Amundsen region is experiencing rapid thinning, and the Amery region is thinning most slowly.

In response to the problems of premature convergence and easily falling into local optima when using traditional global optimization algorithms such as particle swarm optimization and simulated annealing for dispersion curve inversion, we introduce the bald eagle search (BES) algorithm into the study of dispersion curve inversion. Through inversion analysis of multiple typical geological theoretical models and measured data from the Wyoming region of the United States, the results show that the BES algorithm has strong applicability, stability, and noise resistance in the inversion of Rayleigh wave dispersion curves.

We use the ESPAC method to detect the geological structure below the Mogao Grottoes of Dunhuang using observed data obtained by linear array. The detection results show that the layers determined by microtremor survey method are clearly visible, with significant fluctuations of each layer on the two-dimensional microtremor apparent S-wave velocity profile. The covering layer is thick at both ends and thin in the middle. There is a bedrock intrusion in the middle of profile, and there is a solitary stone with a width of 30 m×40 m. Using geological survey data calibration of the relevant region, we show that the thickness of Quaternary cover layer represented by mixed backfill, fine sand, and gravel sand is about 8 m, and the burial depth of complete bedrock surface is about 30 m. The research results can provide geophysical basis for the protection of cultural relics in the Mogao Grottoes.

We lay a shallow seismic exploration line L1 with a length of 10.77 km extended southward across Serteng mountain piedmont fault. The results show that the Sertengshan piedmont fault is clearly visible on the profile, and the main fault has bifurcations in the upper part, consisting of faults F_P1.1 and F_P1, both of which are normal faults with an apparent inclination towards the south. Combined with geological and geomorphological surveys, the latest active age of the F_P1.1 fault is Holocene. We carry out a composite drilling geological section for the fault F_P1 of the Serteng mountain piedmont fault and distinguish two faults, Fa and Fb. Based on the results of optical stimulated luminescence dating, the faults Fa and Fb are Holocene faults and the latest active age is later than 2.5±0.6 ka BP. The Serteng mountain piedmont fault has a forked structure near the surface, which reflects the multiple activities of the fault in the late Quaternary.

In order to investigate the tectonic characteristics, planar distribution, and active period of the buried fault (Hetan-Guotan buried fault) in the northern margin of Zhongwei basin, Ningxia, we apply the method of shallow seismic exploration to the attitude, character, position and burial depths of uppermost aspects of this buried fault. Furthermore, the composite drilling section explores the exact location and more reliable uppermost point, and we identify the latest active period of this buried fault by a sample dating test. The results show that the Hetan-Guotan buried fault is a normal fault trending near EW and dipping S, extending for approximately 12.5 km. The uppermost point of this fault is buried at a depth of more than 38 m, and the apparent dip of the fault is 75°. The Hetan-Guotan buried fault is not an active fault, because its latest active period was the middle-late middle Pleistocene, and it has been inactive at the end middle Pleistocene and since the late Pleistocene.

Addressing the under-quantified crustal deformation characteristics and the unclear stress-strain coupling relationship of the Ordos block, this study employs a spherical least squares collocation model to calculate the characteristic strain field of the study area's crust and inverts the principal stress distribution using seismic source mechanism data. The results indicate that crustal deformation is primarily concentrated along plate boundaries and within fault basins, with less deformation within the Ordos block itself. Notably, at the junction of the northeastern Tibetan plateau and the Alxa block, the crustal deformation is particularly intense, characterized by strong compression along the plate boundary, with the main deformation mechanism being a coexistence of NW-SE compression and NE-SW extension, with a maximum principal compressive strain rate exceeding 0.05 μstrain. The crust in the study area is under a relatively uniform tensile stress environment, with the direction of the maximum principal stress being nearly horizontal and pointing towards SEE, aligning with the direction of the principal strain in the corresponding area. The minimum principal stress direction is closer to the direction of the principal compressive strain.

Based on the observation data from 163 GPS continuous stations in Qinghai-Xizang plateau and adjacent areas from 2010 to 2020, we solve the GPS vertical coordinate time series. Using the global loading grid data provided by GFZ, the environmental loading displacements are calculated by double cubic linear interpolation method, and the GPS vertical time series are corrected. The results show that the hydrological loading has the greatest influence on GPS station displacement in the study area, which is larger in the southern stations, with a RMS of 9.45 mm(MUET site). By comparing the changes of weighted root mean square(WRMS), annual term amplitude and velocity uncertainty before and after environmental loading correction, it is found that the environmental loading correction is able to weaken the nonlinear variations of vertical time series of most GPS stations in Qinghai-Xizang plateau and adjacent areas and it can accurately improve the velocity accuracy of most GPS stations.

Based on the Sentinel-1A image data covering the epicenter, we use D-InSAR to calculate the surface coseismic deformation field of Xinjiang Wushi M_W7.0 earthquake. We use the quadtree method to downsample the coseismic deformation field, and optimize the geometric and physical parameters of the fault by using the downsampling data as constraint conditions. The results show that the maximum uplift values of ascending and descending orbits are 72 cm and 39 cm, respectively. The seismogenic fault is within the Maidan-Shayilamu fault, which is dominated by thrust and has a small amount of left-lateral strike-slip. The fault strike is 230°, the dip is 67°, and the slip angle is about 45°. The maximum slip on the fault plane is 3.53 m, the seismic moment is 3.78×10¹⁹Nm, and the calculated magnitude is M_W7.02. The results of Coulomb stress show that the Tuoshigan fault, Kuokeshale fault, Dashixia fault, Kurukeyuzumu fault, and northern Kuqi fault are all in the stress loading region, on which we need to pay more attention in the future.

We use ascending and descending orbit data of Sentinel-1A satellite to obtain high-precision coseismic deformation fields of Jishishan M_S6.2 earthquake using differential interferometry technology, and employ SBAS-InSAR technique to acquire cumulative deformation time series in the area near epicenter over the past six months. The results show that surface deformation is primarily uplift, with the maximum LOS coseismic displacements of about 6.8 cm and 7.3 cm for ascending and descending orbits, respectively. The rupture mainly occurred at depths ranging from 7 to 15 km underground, with a maximum slip of approximately 0.55 m. Within two months after the earthquake, there is an expanding trend of uplift deformation in the near-field and northwest side of the epicenter. We conclude that the Jishishan earthquake trended northwest, dipping northeast, and the seismogenic fault belongs to the hidden branch fault on southeast side of the southern margin of Lajishan fault zone. The large-scale sudden deformation after the earthquake may be related to pore pressure release, and the surface stability needs further observation.

We propose a method for ground deformation monitoring based on distributed scatterer InSAR(DS-InSAR). The method employs the HTCI algorithm for homogenous pixel identification, utilizes eigenvalue decomposition for phase optimization, determines distributed scatterer(DS) based on spatiotemporal coherence, and establishes a relationship model between DS phase and deformation for time series surface deformation inversion. We use 50 scenes of Sentinel-1A images to obtain spatiotemporal distribution information of ground deformation in Jiangbei region of Nanjing from October 2021 to October 2023. The results show that: 1) The correlation coefficient between DS-InSAR results and PS-InSAR results is 0.731, and the point density increases by 6.22 times. DS-InSAR can more completely reflect the spatiotemporal surface deformation of the study area. 2) DS-InSAR is in good agreement with the measured leveling data, with a maximum error of 5.6 mm, an average error of 2.6 mm, and a root mean square error(RMSE) of 3.0 mm. 3) The geological structures, urban development, and rainfall are the main influencing factors causing ground subsidence.

In traditional techniques, trenching is generally used to reduce the impact of high-speed trains on surrounding buildings. To explore the effectiveness of this method, we use a combination of numerical simulation and on-site experiment to verify the vibration isolation effect of isolation ditches. Based on large-scale finite element software, we compare numerical models with on-site experimental results, and analyze the dispersion characteristics of Rayleigh wave elliptical polarization as high-speed trains pass through viaduct. The results show that when high-speed trains pass through viaduct, a stable surface wave field is formed, which is like the excitation of a single point seismic source. When an isolation ditch is installed on the line, the soil vibration behind isolation ditch shows a certain degree of attenuation, and the isolation effect is obvious.

Based on the barometric effect analysis of the observed cave strain data from five observation stations on the periphery of the eastern Dabie orogenic belt, we find that: 1) The correlation between the observed cave strain and barometric pressure and earth tide is weak for the low frequency domain, the correlation between any two of the three is obvious for the middle frequency domain, while the correlation between the cave strain and barometric pressure for the high frequency domain is less than that for the middle frequency domain, but it increases exponentially with the increase of frequency. The response of cave strain to barometric pressure is prominent for the middle frequency domain. 2) During the nine short-period pressure fluctuation events from 2019 to 2022, the cave strain shows similar characteristics to the barometric pressure change for time domain, frequency domain, change pattern and spatial propagation direction. 3) Combining the different bedrock lithology, covering thickness and topographic characteristics of the five observation stations, we consider that the bedrock of Macheng station is complete and deep, so the barometric pressure response amplitude of Macheng station is the most significant and the average pressure coefficient is the largest, indicating that the rock mass elasticity of its covering layer is good. On the contrary, Jinzhai station's lithology is gneiss, the surface layer is relatively broken, so its barometric pressure response amplitude is the smallest, indicating that the overburden rock mass elasticity is poor.

We calculate the first-order difference, power spectral density and root mean square error and study its time-frequency of SS-Y extensometer data before and after the sealing measures at Wujiahe seismic station, design a virtual sealed filter. The results show that after the virtual seal filter, the noise signal of 0.07 to 0.5 min^－1 is obviously suppressed, and the purpose of safe noise reduction is achieved, which has certain reference significance for improving the observation accuracy.

Based on the data of ground tilt within 500 to 600 km from the epicentre of Wenchuan M8.0, Yushu M7.1, Lushan M7.0, Jiuzhaigou M7.0 and Maduo M7.4 earthquakes that occurred in the north-south seismic belt since 2000, the anomaly analysis of tidal factors, rate analysis, trend turning method, annual variation method and the change characteristics of azimuth and inclination of ground tilt data before the earthquake are carried out. The results show that the tidal factor exceeds 2 times the mean square deviation anomaly about one year before the 5 M≥7 earthquakes, and the anomaly duration is mostly 1 to 3 months. The rate analysis method is suitable for short-term anomaly index extraction, while the trend turning method and the annual variation method are more suitable for medium-and long-term prediction. The magnitude extracted by the trend turning method and calculated by empirical formula is closer to the actual magnitude. The change of dip angle and azimuth angle is more prone to quasi-synchronous anomalies in places far from the epicenter before the earthquake.As the distance to the epicenter decreases, the number of anomalies diminishes, and most of them are single anomalies in either azimuth angle or dip angle.According to the characteristics of ground tilt anomaly and magnitude prediction at present, it is considered that the entropy of ground tilt amplitude factor at present is mainly over-threshold anomaly, and the anomaly of trend turning extraction is concentrated at the junction of Gansu, Qinghai and Sichuan, and the predicted magnitude is high. The regional stress level at the junction of Gansu, Qinghai and Sichuan is still high after the Jishishan M6.2 earthquake. The distribution characteristics of the azimuth angle and dip angle of the ground tilt are similar to those observed before Wenchuan M8.0 and Lushan M7.0 earthquakes.

Early research on broadband seismometer azimuth mainly based on the P-wave particle polarization principle and calculates the angle corresponding to the minimum value of P-wave energy on the lateral component to obtain the angle between the north-south direction of seismometer and the geographic north pole. In addition, the elliptical motion characteristics of Rayleigh waves can be used to estimate the seismometer azimuth of stations with azimuth deviation. We estimate the seismometer azimuth deviation of 20 stations of CENC based on the two different methods. The results show that the azimuth deviation calculated by the two methods is in good agreement, indicating that Rayleigh wave analysis can be appropriately added in future seismometer azimuth detection.