This paper introduces the key technology, refined process, and differences in mainstream software packages for optical coseismic deformation extraction. Geoscientific operators such as displacement gradient, curl, dilatation, and shear strain are derived based on the optical coseismic deformation field. Taking the M_W7.4 earthquake in Maduo, Qinghai province in 2021 as an example, we test the refined process of coseismic deformation extraction based on Sentinel-2 optical images. The results indicate post-processing of subpixel correlation matching results can effectively eliminate white noise and additive noise caused by orbit error, strip error, scenes and sensor factors, highlight deformation details, and more objectively describe the coseismic deformation spatial distribution.

Aiming at the problems of low positioning accuracy and poor reliability in areas without CORS services, we propose a method for differential positioning using a self-established base station with smartphone. The method uses an external antenna to improve the quality of GNSS observation data and uses devices such as RF shielding boxes to set up a self-established base station. The Huawei Mate40 smartphone is used as a mobile station, and RTK positioning is performed with both traditional CORS base station and self-established base station. Static, walking, and cycling experiments are designed to evaluate the service capability of self-established base station. The experimental results show that in the static experiment, the RTK positioning accuracy of Huawei Mate40 smartphone with self-established base station can reach centimeter-level accuracy. In the dynamic experiment, the RTK positioning accuracy of Huawei Mate40 smartphone with both self-established base station and CORS reference station can reach decimeter-level accuracy, with a difference in planar positioning accuracy of about 0.1 m between the two methods. The self-established base station based on a smartphone can provide stable reference station services and meet the needs of surveying and mapping work in specific scenarios.

Global navigation satellite system(GNSS) coordinate series accuracy is mainly affected common mode error(CME) influence. In order to improve the accuracy of GNSS coordinate series, this paper adopts variational bayesian independent component analysis(vbICA) method to extract CME of coordinate series of 20 GNSS stations in the experimental site, and uses distance correlation coefficient and root mean square(RMS) as indicators to evaluate the filtering effect of the original coordinate series. The filtering performance of vbICA method is compared with PCA and ICA. The results show that the filtering effect of vbICA is obviously better than PCA and ICA. After vbICA filtering, the RMS of residual coordinate series in E,N,U direction decreases by 36.57%, 31.63% and 10.97% on average. Distance correlation coefficient decreased by 60.53%,56.84% and 25.80% on average. Considering the optimal noise model and excluding CME, GNSS velocity field estimation is more reliable and accurate, effectively improving GNSS coordinate series accuracy, and providing reliable data support for geodynamic research.

In order to study the coseismic deformation and seismogenic fault slip characteristics of the conjugate earthquakes sequence that occurred in the east Anatolian fault system on February 6, 2023, we use D-InSAR and POT techniques to obtain the coseismic deformation field of the earthquake sequence with the Sentinel-1A data released by ESA. Based on the distributed slip model, we study the geometric form and refined slip distribution inversion of seismogenic faults after data quadtree down-sampling. The results show that the deformation trend of coseismic deformation field of the conjugate earthquakes presents an opposite change trend, and the seismogenic faults are located in the east Anatolian fault system dominated by left-lateral strike-slip. The rupture fault of M_W7.8 earthquake is on the main fault zone, with a maximum slip momentum of about 10.5 m and an average slip angle of 3.74°. The rupture fault of M_W7.5 earthquake is mainly on the Sügür fault, with a maximum slip momentum of about 11.8 m and an average slip angle of 1.05°. The joint analysis on focal mechanism solution given by USGS and GCMT shows that the two major earthquakes are mainly left-lateral strike-slip earthquakes with a small dip-slip component, and the occurrence of this earthquake sequence is an important manifestation of the present tectonic movement of east Anatolian fault zone.

Using StaMPS technology, based on the images of 133 ascending orbit and 95 descending orbit covering Beijing capital international airport from 2017 to 2021, we research the ground subsidence around the airport and the stability of cracks in the interior of the site. The results show that the image monitoring results of ascending and descending orbit are in good agreement. A subsidence funnel is formed in the south of the airport and the south of the Wenyu river. The maximum deformation rate inside the funnel is over 40 mm/a, and the subsidence funnel is distributed along the Wenyu river. We verify the internal coincidence accuracy of the monitoring results of the ascending and descending orbit images. The results show that the deformation rate difference of more than 90% common pixels is between ±10 mm/a, which proves the consistency of the monitoring results of the images. The time series deformation results of feature points show that the subsidence near Jinzhan township, Fuhao village and Huangjinhuayuan community is serious, and the maximum cumulative shape variables exceed 250 mm, 150 mm and 110 mm, respectively. It can be seen from the overall deformation results of the airport and the time series and profile results on both sides of the ground fractures that the difference deformation of the surface on both sides of the ground fractures is significantly compared, and the boundary of the deformation difference is more consistent with the location of the ground fissures.

We study the data of Maduo M_S7.4 earthquake in Qinghai province on May 22, 2021 recorded by second sampling YRY-4 borehole strain gauge and the resampling seconds of BBVS-120 seismometer observed at Gaotai station. We carry out comparative analysis of data variation characteristics, seismological phase morphology and spectral characteristics. We find that the coseismic record of borehole strain second sampling data is clear, and the coseismic record satisfies the self-check characteristics of the four-component borehole strain observation. Both sets of instruments can record the seismic phase of the earthquake, the seismic phase morphology is similar, and the seismic phase arrival time is basically the same. The frequency spectrum and time-frequency diagram of the two sets of instruments are similar, the spectrum components are close, but the frequency distribution and amplitude change are different. This is related to the observation principle, component(direction finding) orientation, frequency bandwidth and observation sensitivity of the instrument. To further analyze the dynamic significance of borehole strain, we conduct space projection of borehole strain at different time nodes, and combined with the relative orientation of the earthquake epicenter and the station, we find that the southwest northeast 2323 and 2324 components, which are approximately close to the epicenter pointing station, and the 2321 and 2322 components distributed perpendicular to the epicenter pointing station, are in opposite tension and compression states. This may be related to the propagation laws of P and S waves.

In this paper, the glacier deformation is obtained by using offset-tracking technology as a supplement to SBAS-InSAR, and the pre-disaster deformation of Sedongpu basin is calculated by using two technologies from January 2018 to October 2018, and the pre-disaster deformation characteristics and influencing factors are jointly analyzed. The results show that the glaciers and gullies in Sedongpu basin were deformed before the ice avalanche occurred on October 17, 2018. The trend of the main deformation area of glacier is first accelerated, then gentle and then accelerated, with the deformation of -7.69 m from July to September. The sediments in channels showed a long-term downward trend, and the deformation rate accelerated after July. The temperature rise is the main factor for the occurrence of debris flow disaster. The combination of SBAS-InSAR and offset-tracking can meet the monitoring requirements of different deformation magnitudes, and can be used for early identification and deformation inversion of ice avalanche disasters, providing a reference for ice avalanche disaster prevention and control in the Tibetan plateau.

To improve the positioning accuracy of mobile intelligent terminals, we analyze the observation data of multiple satellite systems collected by Xiaomi Mi8 and Huawei Mate20 smartphones, estimate the parameters of signal-to-noise ratio model based on pseudorange residuals of different satellite systems, and finally carry out the static pseudorange single-point positioning experiment. The results show that the pseudorange accuracy of BDS and GPS observed on mobile phones is close to each other and is higher than that of GLONASS. The correlation between pseudorange residual and SNR is stronger compared to elevation angle. In the parameter estimation of SNR model, the fitting effect of Xiaomi Mi8 is better than that of Huawei Mate20. The fitting effect of BDS is worse than that of other satellite systems, and the horizontal positioning and elevation positioning accuracy of SNR model after parameter fitting are 2.37 meter and 8.38 meter, respectively, which is about 10% higher than that of elevation model.

We propose a gait recognition model that fuses long short-term memory(LSTM) and convolutional neural network(CNN), the model can automatically extract activity features and classify them using a small number of model parameters, and we utilize this model for user identification.  The experimental results show that the recognition accuracy of the model is about 97.68 % and the loss value is about 0.05, which significantly improves the recognition rate compared to other models.

Considering that BP neural network model ignores the temporal correlation of slope monitoring data, and LSTM model falls into local optimality due to the subjectivity of hyperparameter selection, we propose a slope deformation prediction model based on the combination of genetic algorithm and long short-term memory network(GA-LSTM). We utilize the global search ability of genetic algorithm and the advantages of LSTM forecasting time series data. Taking the slope of Haiming mining open-pit as the research object, we adopt BP neural network model, LSTM network model and GA-LSTM network model, respectively, to predict and analyze the GNSS49 deformation of the slope monitoring point. We compare the times for each model to reach the convergence condition. The research results show that: The time difference between GA-LSTM model and other models to reach the same convergence condition is not large. The fitting accuracy of GA-LSTM model is between 0.1 mm and 0.2 mm, which is 5 to 7 times that of LSTM neural network model and 10 to 20 times that of BP neural network model, with high accuracy and stability. The predicted value is basically consistent with the actual monitoring data, which can provide scientific basis for the safe production, management and decision control of mine slope.

Using the precise ephemeris data from November 2022 for seven consecutive days as a reference, we evaluate and analyze for accuracy the real-time precise products from the 5 organizations(CAS, CNES, GFZ, SHA, and WHU). The experimental results reveal the following: CAS currently provides the highest quantity of real-time precise products for BDS-3 satellites, but the clock accuracy for MEO satellites is the lowest, exceeding 0.4 ns. GFZ’s IGSO satellite products have the poorest quality, with radial orbit errors exceeding 30 cm and clock accuracy greater than 0.8 ns. WHU’s product data quality is best, with radial orbit errors better than 4 cm and clock accuracy of about 0.16 ns, but it has only 19 available satellites. In the positioning domain, we conduct a comparative analysis of real-time precise products from various agencies using dual-frequency, ionosphere-free dynamic real-time Precise Point Positioning(PPP) techniques. The positioning results indicate that the real-time products from CNES, SHA, and WHU exhibit similar levels of positioning accuracy. The overall positioning error in both horizontal and vertical directions is approximately 0.2 meters. Taking into consideration the available number of satellites and the quality of real-time product data, we recommend that real-time PPP users utilize either CNES or SHA’s real-time products.

Considering the high stability of high-performance hydrogen clocks and the strong correlation between clock offset series epochs, the receiver clock offset with additional prior information constraint is tested for precise point positioning(PPP) timing. The results based on B1C/B2b combination of BDS-3 show that compared to traditional timing models, the precision timing models with additional prior information have higher timing performance, especially for the short-term stability which has an improvement up to 60%. In addition, the PPP accuracy of B1I/B3I and B1C/B2b combinations of BDS-3 is basically equivalent, which can achieve positioning accuracy better than 0.5 cm and about 2 cm in horizontal and vertical direction, respectively. Owing to the better observation data quality of B1C/B2b, the positioning accuracy is improved by 13.8% compared to the B1I/B3I combination.

From the aspects of consistency and correlation, we compare and analyze the observation data of the two sets of volumetric strain gauges before and after sensor replacement in Suqian earthquake monitoring center station. We find that the observation system of the newly installed volumetric strain gauge is stable, the observation data are reliable, and the observation data are highly consistent and correlated with the historical data of the original volumetric strain gauge. We consider that the two sets of data before and after the replacement can be regarded as continuous and correlated whole data for the study of crustal stress-strain field in this region.

Using least squares and iterative algorithms for 5 d simultaneous co-location comparison observations at Anqiu seismic station, we process the data of A10-057 absolute gravimeter, FG5-265 absolute gravimeter and superconducting gravimeter(iGrav). The final calibration factor factors of FG5-265 and A10-057 precision measurement iGrav-053 are -883.929 4 ns^-2/V and -884.134 ns^-2/V, respectively, and the calibration accuracy is 0.048 26% and 0.093 7%, which are better than 0.1%. At the same time, we compare the differences between the calibration work of FG5-265 and A10-057 in terms of various measurement indexes and the selected measurement logarithms on the calibration results, and exemplify the requirements of calibration factor for multiple scenarios, which finally proves that the A10 model absolute gravimeter has the capability of calibrating relative gravimeters and provides a reference for the subsequent calibration of relative gravimeters.

We constructed models for changes in atmospheric and terrestrial water mass in the Three Gorges region. Then, using GNSS, GRACE-FO, and environmental mass change models, we calculate and analyze the vertical crustal deformation caused by environmental load from 2019 to 2022 in the region. At last, we discuss the differences in calculating environmental load vertical deformation using the spherical harmonic method based on GRACE-FO data and Green’s function method combined with the mass change model. The research reveals the vertical deformation of terrestrial water load of the two methods exhibits a certain consistency in spatiotemporal distribution, but the mass change model shows higher accuracy and spatial resolution. We calculate the environmental total load vertical deformation at CQWZ and HBZG stations, based on the quality change model. The correlation coefficients between deformation and GNSS measured results reached 0.88 and 0.83, respectively. The vertical deformation rates of the crust in the Three Gorges reservoir area and Dongting lake basin from 2019 to 2022 are 0.5 to 0.7 mm/a and 0.6 to 1.5 mm/a, respectively. We attribute this to the decrease in water level in the region in 2022, leading to crustal rebound. The crust near the Three Gorges reservoir exhibits a pattern of rising in summer and sinking in winter, with vertical deformation amplitudes ranging from -5 to 18 mm, primarily driven by reservoir water storage and atmospheric load.

This article selects the continuous observation data of three different models of gravimeters(gPhone, DZW, and GS-15) observed at the same site of Jixian seismostation throughout 2022, studies the response of different types of instruments to environmental noise, calculates the gravity noise levels of the three types of gravi meters, calculates the seismic noise levels in the seismic frequency band(200-600 s), and compares them with the seismic noise levels of gPhone gravimeters nationwide. The research results indicate that: 1) when the frequency is below 10^-3 Hz, deducting solid tide and pressure correction can significantly improve the level of gravity noise; 2) The gravity noise levels of different instruments at the same station are different. The background noise level of the gPhone gravimeter is lower than that of the DZW gravimeter and GS-15 gravimeter, with an SNM value of 3.355; 3) The average noise level in the seismic frequency band of the gPhone gravimeter nationwide in 2022 is 5.418, while the average noise level at Jixian station is 3.465, which is lower than the national noise level. The research results can provide reference for the research and application of three types of gravimeter observation data.

The original curve analysis method and normalized variation rate method were applied to analyze the data changes of four earth resistivity stations within 400 km of the epicenter of Maduo M_S7.4 earthquake on May 22, 2021. The following results were obtained:1)Before the Maduo earthquake, the data of four earth resistivity stations showed different degrees of anomalous changes, among which the original curve changes of the Maqu NW, Jinyintan EW, Ganzi N10°E, and Lanlongkou EW channels were the most obvious, which manifested hour value jumping changes, accelerated changes in the daily mean values and curve turning changes, as well as trend changes in the monthly mean values of the broken and preserved annual variation patterns;2)The normalized rate curves of Maqu NW, Jinyintan EW, Ganzi N10°E, and Lanlongkou EW all exceeded the threshold before the Maduo earthquake, but their respective normalized rate patterns are different;3)The comprehensive analysis concludes that the anomalous changes in the earth resistivity data of the four stations are related to the gestation and activity of the Maduo M_S7.4 earthquake.

This paper introduces the research progress, standardized test and experimental observation on seismic station of the JCZ series ultra broadband seismometer JCZ-360. The results show that the JCZ-360 ultra broadband seismometer can effectively suppress the influence of external atmospheric pressure, external magnetic field interference and temperature change on the instrument. Its performance is more stable and noise level is lower at the ultralow frequency terminal. The JCZ-360 ultra broadband seismometer can not only observe full-band seismic waves, but also record information such as solid tides and free oscillation of the Earth. It has the comprehensive observation ability of traditional seismic and traditional geophysical field.

Very long baseline interferometry(VLBI) plays an important role in China’s Lunar Exploration Program(CLEP). In order to obtain the accurate positioning of the lunar probe, achieve the accurate orbit determination function and complete the orbit correction during the flight of the probe, it is necessary to use the VLBI station to observe the lunar probe in real time. In this paper, we mainly use the arithmetic mean(AM) and standard deviation(STD) as precision evaluation indexes. We analyze the VLBI measured data of Chang’e-4 probe, relay satellite and Chang’e-5 probe from Shanghai Observatory for the data stability of the total observation period. Based on the simultaneous observation of the S and X bands of Chang’e-4, we emphasize the quality analysis of the data of different frequencies. We carry out time delay, time delay rate measurement error and check residual analysis for each working section of the detector, and the correlation between the motion of the detector and the data change. The results show that Chang’e-4 has the highest accuracy of 1ns among the three types of probes. Chang’e-5 probe has better observation stability than the other two types of detectors. Different ground stations have different observation accuracy of the detector, and the measured data show different characteristics in different working stages of the detector.

To compare the positioning performance of the new signals and old signals of Beidou-3 satellite navigation system, we conduct a comprehensive evaluation of BDS-3 precise point positioning with new signals B1C/B2a using two-week observation data from 17 MGEX stations. The results show that the accuracy in E, N, U directions of static PPP with BDS-3 B1C/B2a was 1.3 cm, 0.8 cm, and 1.9 cm, respectively, while that of kinematic PPP was 2.6 cm, 1.8 cm, and 4.2 cm, respectively. The static positioning accuracy in U direction showed an improvement of 13.6% compared to the BDS-3 B1I/B3I combination, the accuracy in E, N directions were similar. In the kinematic mode, the accuracy in E, N, U directions were similar, with differences within 1 mm. In terms of three-dimensional(3D) error, BDS-3 B1C/B2a static PPP achieved centimeter-level accuracy within 40 minutes, while kinematic PPP achieved decimeter-level accuracy within 5 minutes. The static PPP with the dual-system BDS-3 B1C/B2a+GPS L1/L2 achieved centimeter-level accuracy in three dimensions within 20 minutes, while the kinematic PPP achieved centimeter-level accuracy within 30 minutes. Comparing with dual-system BDS-3 B1I/B3I+GPS L1/L2, the positioning accuracy and convergence speed are basically the same. Overall, the positioning performance of B1C/B2a frequency is superior to that of B1I/B3I frequency.

This paper collects dynamic data from low-cost receivers in three different speed ranges and analyzes the data reception capability, data quality, and navigation positioning performance of multi-system interoperable signals, B1C/L1/E1, and B2a/L5/E5a, within various speed intervals. The results show: 1) As the speed increases, the reception capability of interoperable signals gradually deteriorates. BDS-3 can maintain visibility of more than nine satellites on average. Among the interoperable signals, B1C/L1/E1 exhibits superior data integrity but is more susceptible to data interruptions.2) As the speed increases, the carrier-to-noise ratio of interoperable signals decreases, and cycle slip ration increase. However, the pseudo-range noise, carrier phase noise, and multipath effects are less affected by speed. Notably, B1C/L1/E1 exhibits minimal carrier phase noise and multipath effects. 3) The influence of carrier speed on positioning accuracy has no obvious regularity. The speed and the degree of environmental occlusion affect the positioning accuracy. The multi-system interoperability signals combination positioning has more improvement than the single system positioning performance; BDS-3 has high accuracy in the middle and low speed range, and its precision of PPP is better than other systems by more than 17%.

We use observation data from 5 GNSS/MET stations in Shanghai from July 21 to August 8, 2021 to invert atmospheric precipitable water vapor(PWV) by GAMIT software, and study the relationship between PWV and rainfall in Shanghai and the spatial distribution characteristics of PWV during typhoon “In-Fa”. The results show that the correlation between GNSS PWV and sounding PWV is above 0.9. Before the formation of precipitation, PWV undergoes three obvious rise processes and the precipitation generation time is about 60 h ahead of typhoon landfall.  PWV sharp change will cause a sharp rise or fall in precipitation. After the precipitation, PWV gradually drops below 40 mm. Before typhoon landfall, PWV is basically above 75 mm; PWV above 80 mm is mainly distributed in southern and central areas of Shanghai. After typhoon landfall, PWV is above 80 mm, and higher value areas can reach 90 mm. After the typhoon moved away, the PWV value dropped below 85 mm. The expansion and progression of the high-value area to the northwest is basically consistent with the typhoon path.

The solid tide signal of VP inclinometer is limited by the complex monitoring environment, which contains significant environmental noise. To obtain the real solid tide curve, we propose an improved complete ensemble empirical modal decomposition adaptive noise(ICEEMDAN) based on grey relation analysis for VP inclinometer to suppress signal noise. The method firstly uses ICCEMDAN to decompose the noise-containing signal to obtain several intrinsic mode functions(IMFs), which are sequentially arranged and labeled. Then, based on these IMFs, the evaluation indexes of correlation coefficients, mutual information, R², Adj-R², MSE, SSE, RMSE, MAE, MAPE, we compute sample entropy to construct a reliability evaluation index matrix of the IMFs. Finally, grey relation analysis(GRA) is used to calculate the correlation coefficients and degrees between various evaluation indexes and different IMFs. We sort the IMFs based on the correlation degree, and linearly reconstruct the top ranked IMFs to suppress signal noise. Both the simulation and actual denoising experiments show that the GRA-ICEEMDAN model is better than the classical noise reduction models, such as Kalman filter, 70 order low-pass FIR filter, and Savitzky-Golay. The noise component and effective component can be distinguished significantly, and the reconstruction error and original signal loss after decomposition are very small, so it can be extended to the signal noise reduction of other instruments.

Aiming at the low efficiency of manual interpretation of gravity change anomaly feature region, we propose an automatic identification method using YOLOv5s algorithm to identify the four-quadrant feature area of gravity change, and conducts tests and verification based on the measured gravity change data of the north-south seismic belt. The results show that: 1) our image recognition model can effectively identify the relatively standard four-quadrant distribution feature region, and the accuracy, recall rate and average accuracy of the model prediction results are all in a reasonable range; 2) The model can accurately identify the four-quadrant feature area in the gravity change image of the north-south seismic belt from September 2021 to May 2022, and the Lushan M6.1 earthquake in June 2022 and Luding M6.8 earthquake in September 2022 in the feature area occurred successively. The results show that the proposed method has a good application potential for the screening of gravity anomaly regions and the study of potential seismic risks. 3) The recognition ability of the model for the non-standard four-quadrant feature area with obvious distortion is still insufficient, and it is still necessary to build more data training sets with more reasonable labeling to further improve the universality of the model for the recognition of the four-quadrant feature area.

Using seismic data of Jianghan-Dongting basin and its surrounding areas from historical records to 2021 to analyze the spatiotemporal distribution characteristics of earthquakes, we obtain the relationship between deep tectonics and earthquakes by using the hypoDD algorithm to relocate 788 earthquakes, and analyze the characteristics of tectonic stress field by using the P-wave first motion method to calculate the focal mechanism solutions of M_L≥2.8 earthquakes. The results show that earthquakes are distributed unevenly in space, the seismicity of basin boundary is stronger than that inside basin, and there is an obvious periodic rule of alternating quiet and active in time. The relocated earthquakes are distributed in clusters in NW and NE directions in Ningxiang, Shimen, Yuanan-Dangyang, Nanzhang- Jingmen, and Ezhou-Huangshi, and the seismogenesis of this five regions are closely related to fault tectonic activity. The type of focal mechanism solution is mainly thrust fault, the dominant orientation of P-axis is nearly EW, and its plunge angle is almost horizontal, the orientation of T-axis is mainly SN and NE, and its plunge angle is large. The horizontal collision between the Indian ocean plate and the Eurasian plate result in the formation of a nearly EW tension stress field in the Tibetan plateau, which pushes the basin eastward. In addition, the Philippine sea plate subducts northwestward and the Pacific plate subducts westward, resulting in the formation of a nearly EW compression stress field in the basin, which make the regional fault structure prone to vertical differential movement, and then led to the gestation and occurrence of earthquakes in the Jianghan-Dongting basin and its surrounding areas.

Using numerical simulation based on the existing station layout of Shanxi Network, we quantitatively analyze the effects of crustal velocity model, network layout and seismic phase picking accuracy on seismic source location. The results show that the three factors have different effects on the accurate location of seismic source. In the crustal velocity model, the upper crust velocity has the greatest influence on the epicenter location, and the epicenter location is more sensitive to the change of Moho velocity. The deviation of epicentral position caused by a single change of crustal velocity model is usually less than 5 km, the focal depth is very sensitive to the change of crustal velocity model, especially the Moho depth, and the maximum deviation may exceed 20 km. Without considering other factors, the maximum deviation between the epicenter position and the focal depth measured within 4 s with P-wave picking accuracy is not more than 2 km and 5 km. When the crustal velocity model is suitable and the seismic phase picking accuracy is high, the station layout with the maximum void Angle of 0°-180° has a better constraint on the focal location, the epicenter deviation is basically less than 1 km, and the focal depth deviation is slightly larger, about 2 km.

Based on the results of the first national earthquake disaster risk survey, we calculate and analyze the proportional relationship and spatial distribution characteristics of peak acceleration under different levels of exceedance probability in Hubei region. Using the macro site category data of Hubei Province, we calculate the proportion relationship of surface peak acceleration under frequent earthquakes, basic earthquakes, and fortified earthquakes. In the 0.05 g acceleration zone, the mean of the 50 years exceedance probability of 63% and 10% peak acceleration ratio(R₆₃/R₁₀) for sites in Hubei Province is 0.31, and the mean of the 50 years exceedance probability of 2% and 10% peak acceleration ratio(R₂/R₁₀) is 1.81; in the 0.10 g acceleration zone, the mean of R₆₃/R₁₀ is 0.30, and the mean of R₂/R₁₀ is 1.80; in the 0.15 g acceleration zone, the mean of R₆₃/R₁₀ is 0.17, and the mean of R₂/R₁₀ is 1.98. We comparatively analyze the proportion required by mandatory national standards such as current seismic design specifications for buildings and China’s seismic parameter zoning map. We infer that the seismic danger is reasonably safe in Hubei province, if rules of code for seismic design of building are followed. The peak ground motion acceleration value of frequent earthquakes should be adjusted to not less than 1/3 of the basic peak ground motion acceleration when conducting earthquake hazard analysis, earthquake disaster risk prevention and control work in high intensity areas, such as Zhushan and Zhuxi in Hubei province. The research results of this article will contribute to the promotion and application of earthquake risk survey results in Hubei province.

By fusing the observation data with the model，data assimilation provides an effective solution for realizing accurate mapping of physical and mathematical models to solid Earth as much as possible. We review the application and research status of data assimilation method in various branches of solid Earth geophysics, and make a preliminary discussion on the urgent problems of data assimilation method in solid Earth geophysics.

We compare and analyze the scale factors of long baseline calibration and datum solution of 5 CG-6 relative gravimeters, and process the data of gravity network in Guizhou of CMONOC in 2022 and 2023 using different scale factors. The results show that the scale factors of CG-6 relative gravimeters vary over time, and the precision of processing results is better by using the datum solutionscale factor.

This paper is based on the AR products from CODE, GFZ, CNES, PRIDE Lab, and in-house AR products for the performance assessment of PPP-AR in terms of convergence time, time to first fix and positioning accuracy. The experiment uses seven-day observation data from 40 IGS stations in 2022 and precise products of each AR product. The results show that under the static solution mode with confidence level of 95%, five products have the most obvious improvement in positioning accuracy at the time of 1 h, which are 46.58%(3.4 cm), 41.10%(3.0 cm), 45.21%(3.3 cm), 34.25%(2.5 cm), and 41.10%(3.0 cm), respectively. In the simulation-kinematic solution mode, the positioning accuracy of the five products in the E and N directions can reach the millimeter level, and the accuracy of the U direction is slightly improved than that of the floating point solution, among which the accuracy of GBM product is the least improved, and 72.73%(2.4 cm), 47.37%(0.9 cm) and 5.41%(0.2 cm) were increased in E, N and U directions. WUM and COM products had better improvement effect. They were 81.82%(2.7 cm), 63.16%(1.2 cm), 24.32%(1.1 cm) and 81.82%(2.7 cm), 63.16%(1.2 cm), 15.58%(0.8 cm).

The precipitable water vapor(PWV) retrieved by MODIS is continuous planar data, but the accuracy is not high. The PWV accuracy of GNSS water vapor detection technology is high, but it is discrete point data. Therefore, we combine the advantages of both, propose a MODIS water vapor correction method that combines inverse distance weighting and Fourier transform, and use GNSS PWV to correct MODIS PWV products. The GNSS data and MODIS water vapor products in Hong Kong are used for experimental verification. Firstly, the spatial interpolation problem is considered to make GNSS PWV and MODIS PWV consistent at spatial points. By comparing the accuracy of six interpolation algorithms with different MODIS pixel points, it is found that the algorithm with 5 interpolation parameters has the best effect, and the inverse distance weighting method has the highest accuracy, with an average deviation of -0.99 mm. Secondly, considering the water vapor correction problem, three models are constructed to correct MODIS PWV. It is shown that the root mean square error improvement rate of Fourier transform model can reach more than 70%. The MODIS water vapor correction method of the new model can weaken the influence of local data, and more accurately reflect the water vapor distribution in the region.

We process 69 Sentinel-1A satellite images using SBAS-InSAR from July 2018 to August 2019, and obtain surface deformation in Shuicheng district, Liupanshui city as dynamic evaluation factors to address the lack of dynamic feature data in traditional landslide susceptibility studies. The results show that, by fusing ten static evaluation factors and InSAR deformation feature data as dynamic evaluation factors, in a weighted information model coupled with analytic hierarchy process(AHP) and information volume method, the model performance improves approximately 13.3% compared to using only static feature data. The area under the ROC curves is 0.756 02 and 0.888 68, respectively. To assess zoning accuracy, we overlay historical disaster sites on two types of zoning maps. Compared to scenarios without the inclusion of deformation features, the introduction of deformation features corrected approximately 12.44% of misclassified areas, significantly enhancing zoning reliability.

We utilize 195 finite fault models of strong earthquakes (M_W≥7.0) released by USGS from 1990 to 2023. We employ the method of least squares fitting to derive new empirical relationships between moment magnitude(M_W) and rupture length(RL), rupture width(RW), and rupture area(RA), respectively. Taking strike-slip, reverse, and normal faulting earthquakes as examples, we obtain geometric parameters of different fault types based on the new empirical relationships, which we then utilize to calculate coseismic Coulomb stress changes. The results indicate that the spatial distribution of stress enhancement and decrease obtained using the new empirical formulas closely align with the results obtained from actual rupture models, thus providing the effectiveness of the new relationships.

The background noise of the second sampling data of four kinds of broadband instruments in Xinjiang during quiet period is analyzed, and the time-frequency characteristics of the signals recorded by various instruments under seismic waves and wind disturbance events are discussed. The results show that the noise level of RZB-2 borehole strainmeter is the best, and the response ability of VP type vertical pendulum to high-frequency signals(microseisms frequency range) is the best. Whether the instrument can record more geophysical signals or high frequency information is not only related to its own noise level, but also related to its response ability to the signal in this frequency band.

We study the Jiuzhaigou M_S7.0 earthquake in August 8, 2017, using observation data from 10 broadband seismometers near the epicenter before the earthquake, to calculate the permutation entropy of ground motion velocity. We investigate the relationship between the temporal-spatial variation characteristics of permutation entropy and the formation of large earthquakes. The results show that there were two abnormal episodes of permutation entropy in late July 2017; the largest one occurred at the end of July 2017. There was an entropy reduction process at all 10 stations. Among them, the decreases of permutation entropy at Maerkang(MEK), Zhouqu(ZHQ), and Diebu(DBT) stations were relatively large, with entropy values of 0.75, 0.76, and 0.79, respectively, which decrease by 12%, 12%, and 10% compared to the mean, respectively. The decrease of entropy at multiple stations indicate that there was an orderly vibration source in the crustal movement. The spatial evolution images of the low-value areas in the northeast and southwest of epicenter also indicate that there is a correlation between the abnormal change of entropy and the formation of this large earthquake. Based on previous research results, we believe that the eastward movement of Qinghai-Tibet plateau block and its blockage by the north China block and the south China block resulted in the energy accumulation of this earthquake. The Jiuzhaigou M_S7.0 earthquake was triggered by upwelling and rotation of the lower crustal material after it was blocked by the Sichuan basin.

We utilize Sentinel-1 data to obtain the coseismic deformation of the 2022 Luding M_W6.7 earthquake. Then. we invert the fault geometry parameters and slip model with the InSAR, GNSS, and strong motion data as constraints. The optimal fault strike, dip, and rake angles are 164.3°, 73.7°, and -3.2°. The fault ruptures to the surface, and fault motion is dominated by the left-lateral strike-slip and with a slight dip-slip. The fault slip is concentrated on the depths of 0-18 km, and the peak slip reaches 1.67 m at a depth of 7 km. We further estimate the fault kinematic parameter based on the screw dislocation model by the interseismic GNSS velocities. The fault locking depth is 17.8 km and the long-term slip rate is 10.8 mm/a. The estimated seismic moment accumulation of the Moxi segment is 9.52×10¹⁹ Nm since 1786. However, the 2022 Luding earthquake only released 12.3% of the seismic moment accumulation, indicating that the Moxi fault has a high earthquake potential. The Coulomb failure stress in the northern of the Anninghe faut is positive, which suggests the high seismic risk of the Anninghe fault.

This paper introduces the methods and steps for estimating multi-GNSS multi-frequency code biases and validates the effectiveness of estimating inter-frequency code biases using a multi-GNSS ionospheric modeling approach. We compute daily solutions for various code biases using MGEX network observations from January 2019 to July 2023. We further analyze the accuracy of various code biases. The results indicate that the multi-GNSS multi-frequency OSBs calculated in this paper exhibit an average weekly stability ranging from 0.07 to 0.26 ns. Among them, the average weekly stability of BDS-2 and BDS-3 multi-frequency OSBs are 0.17 to 0.26 ns and 0.13 to 0.21 ns, respectively. The consistency of various types of DCBs with products from DLR and CAS can be maintained within 0.3 ns. This research is not dependent on external post-processing products and can calculate code biases with both a rapid turnaround time and high precision.

Starting from the theoretical basis of nonlinear adjustment precision evaluation, we review the current research status of the two types of precision evaluation methods. We describe the basic principles of the corresponding method and analyze the advantages and disadvantages of each method. In addition, we look forward to the research direction of nonlinear adjustment precision evaluation.

Based on the satellite orbit characteristics of BDS GEO, IGSO, and MEO, we use multi-point hemispherical grid model(MHGM) and sidereal filtering(SF) method to establish a multipath error correction model for a mixed constellation of BDS. After applying the model to correct multipath errors, the post-fit carrier phase residuals for BDS precise point positioning(PPP) are significantly reduced, and the positioning accuracy in E, N, and U directions is improved by 41%, 37%, and 38%, respectively, with an overall increase in convergence speed of 31%.