We use multiple SAR satellite data, and adopt the time-series InSAR technique to restore the ground deformation time series of the Sebei gas field since its formal development in 1996. The results show that the surface of Sebei No.1 gas field remained stable from 1996 to 2003, experienced significant uplift from 2003 to 2005, and rapidly subsided from 2005 to 2018. We use the uniform elastic half-space model to invert the relationship between natural gas exploitation and ground deformation in the Sebei No.1 gas field from 2015 to 2018. It’s shown that the amount of surface subsidence in the Sebei gas field increased with the increase of natural gas exploitation volume, while the exploitation depth increased first and then stabilized at 2 300 m after 2017. Furthermore, we also calculate the volume change of underground natural gas reservoir inverted by InSAR under standard conditions. The results show that the difference between the InSAR inversion results and actual statistical data is very small, verifying the reliability of InSAR monitoring and inversion results. The results of this study can provide important ground deformation data for the safety production of Sebei gas field and the healthy operation of surrounding infrastructure.

Deformation monitoring was conducted in Enshi, Hubei province based on SBAS-InSAR method using 97 Sentinel-1A satellite images from 2019-01 to 2022-05. The results show that there are multiple landslide clusters in the study area with a maximum sliding rate of 49 mm/a. The relationship between deformation and slope based on the slope map of the study area generated by external DEM reveals that the sliding areas are mainly located in mountains with slopes ranging from 20° to 40°, so the slope and aspect factors need to be considered during railway route selection. It is found that inland landslides away from rivers tend to slide faster in the rainy season and slow down after the rainy season, while riverbank landslides tend to slide slower in the rainy season and slide faster after the rainy season. Combined with the analysis of optical images and geological survey data, it can be seen that the InSAR monitoring results are basically consistent with the actual situation. The research results can help to understand surface deformation trends and causes in Enshi, Hubei province, and indicate that the time-series InSAR technology can be used for landslide census and early warning of rail transportation projects. The landslide monitoring results can provide an important reference basis for the route pre-selection of high-speed railway.

Based on 49 Sentinel-1 images, we combine SBAS-InSAR and CR-InSAR to monitor the deformation of Ankang airport with expansive soil for two years. The results show that there are three obvious unstable slope areas, which are highly coincident with the airport filled areas. The unstable slope is far away from satellite along the line of sight. The deformation range in space is from point to surface, and the deformation rate in time is gradually slowing down. Combined with the rainfall data, we find that the deformation rate of expansive soil slope slow down obviously in the summer rainfall period, and even uplift. Comprehensive analysis shows that the special deformation of airport slope area is closely related to expansive soil used in the construction, and the deformation of Ankang airport is still continuing.

We use Sentinel-1A data from July 2017 to April 2019 to monitor and analyze the landslide deformation rate and displacement time series in the area of Ahai power station, and evaluate the reliability of SBAS-InSAR monitoring results using GPS data in the same period. The results show that the landslide deformation gradually increases from the rear edge to the front edge of the slope during the InSAR observation time, with the maximum annual deformation rate of 136.7 mm/a and the maximum cumulative deformation of 216 mm. The SBAS-InSAR result is relatively close to the measured GPS data in the area with small deformation and has high accuracy. However, in the area with a large deformation gradient, there are still some differences between SBAS-InSAR and measured GPS data.

To improve the spatio-temporal resolution and accuracy of land deformation monitoring, we  adopt the fusion method of CORS network and time series InSAR  to study the vertical deformation in Beijing from 2018 to 2020. First, we remove the very shallow surface impact from the InSAR monitoring data. Then, the data of CORS stations are reconstructed in low frequency. Finally, based on CORS network, the InSAR monitoring time series is integral adjusted to obtain the fusion deformation. The results show that the fusion method of CORS network and InSAR monitoring can effectively use the continuous observation advantage of CORS network to obtain continuous and consistent deformation with high spatio-temporal resolution. The fusion method has certain advantages in building high-resolution and high-precision land deformation time series. In the vertical direction, the land subsidence in Chaoyang district, Tongzhou district and mid-southern Daxing district is the most obvious, and the maximum average annual deformation rate reaches -90 mm/a. The mid-western Changping district, western Haidian district and eastern Mentougou district have relatively obvious uplift, and the average annual deformation rate is about 10-20 mm/a. The average annual deformation rate in other regions is about -10-10 mm/a, with relatively small changes and relative stability.

In order to accurately grasp the deformation law of special landslide, based on the landslide deformation monitoring results, we master the existing deformation characteristics through statistical analysis. Using SOA-MKELM-GRNN model, M-K analysis and Spearman rank test, we analyze the subsequent development characteristics of cumulative deformation sequence, deformation rate sequence and deformation acceleration sequence. The purpose is to fully grasp the deformation law of high-elevation and long-runout bedding rock ancient landslide through deep information mining of various deformation sequences. The results show that in the aspect of existing deformation characteristics analysis, the cumulative deformation of each monitoring point has a continuous increasing trend, and the maximum cumulative deformation has reached 205.51 mm. The deformation rate has a large fluctuation range, and its distribution proportion is relatively large in the range of 1.0-2.5 mm/d. The acceleration sequence value is relatively large in the early stage and slightly small in the later stage, indicating that the deformation acceleration of the landslide is stronger in the early monitoring stage. In terms of the analysis of subsequent deformation development characteristics of the landslide, the cumulative deformation will still further increase, but there is a certain difference in the deformation degree, that is, the development law of subsequent deformation rate and acceleration is inconsistent. The subsequent deformation of C1 and C3 monitoring points is more unfavorable, so we can focus on the subsequent deformation monitoring of this section.

Based on the two-dimensional finite element method, we use the contact element to simulate the discontinuous fracture process of fault zone, and establish the near-field strong ground motion estimation model of the Jiuzhaigou M7.0 earthquake in Sichuan on August 8, 2017. We also study the key source parameters such as stress drop and yield stress. Based on the reliability test of ground motion parameters using the actual observation waveforms provided by the national strong earthquake data center, we give the PGA distribution, and discuss the characteristics and mechanism of directional effect of near-field strong ground motion. The results show that: 1) With the increase of yield stress and stress drop parameters of the source contact element, the horizontal PGA increases as a whole, and the influence of the former on strong ground motion is more significant. When the stress drop is 8.5 MPa and the yield stress is 4.0 MPa, the relative error percentage of strong ground motion simulation results is less than 40% on the whole, and the relative error of 51JZB and other near-field strong seismic stations is less than 5%. 2) The contour of horizontal PGA simulation results of the Jiuzhaigou M7.0 earthquake is generally elliptical, and the major axis of the ellipse is in good agreement with the strike of seismogenic fault. The maximum value of PGA near the epicenter is about 720 Gal, and decreases with the increase of epicenter distance. The PGA dropped by 16.67% and 22.72% respectively when cross the north section of Longriba fault and Xueshanliangzi fault. The isolation effect of fault zone may be related to the transmission reduction of ground motion along the fault plane.

We use Sentinel-1 data of three tracks to obtain the three-dimensional surface deformation rate field in the Zhangjiakou-Xuanhua basin and its surrounding area by using the PS-InSAR and the least-squares iterative approximation method combining prior conditions. We calculate the slip rate and locking depth of the Zhangjiakou fault and the southern margin fault of Xuanhua basin by profile projection and the mathematical expression for interseismic deformation of dip-slip faults of edge dislocation. The results of fault parameters show that the middle section of Zhangjiakou fault and the southern margin fault of Xuanhua basin have a high locking degree and background condition for strain energy accumulation to occur moderate to strong earthquake.

The present activity characteristics of main faults in Liaoning area are analyzed using cross-fault data. The results of long-term data show that the activities of Yalujiang and Hunhe faults in northeastern Liaoning are relatively stable, and the activities of Jinzhou fault in southern Liaoning and Chaoyang-Beipiao and Dalinghe faults in western Liaoning are relatively active. There is a certain similarity between Jinzhou fault and Chaoyang-Beipiao fault. The 2011 M9.0 earthquake in Japan had a significant impact on the activities of Jinzhou and Chaoyang-Beipiao faults. Since 2015, the activity level of Jinzhou and Chaoyang-Beipiao faults is consistent with its background level and is at a weak activity level.

In order to explore the variation characteristics of b-value before and after the Menyuan M_S6.9 earthquake in Qinghai, we select a time scale of 10 years before the earthquake for time scanning. It’s found that the b-value in the focal area decreases to a certain extent before the earthquake, and then shows a small rebound after the earthquake, which may be related to the post-seismic stress release. Using the catalogs of small earthquakes from Qinghai seismic network since 2000, the spatial scanning of b-value and calculation of Δb-value based on the minimum magnitude of completeness show that the Menyuan M_S6.9 earthquake occurred at the edge of low b-value region, and the Δb-value in the focal area one year before the earthquake did not change significantly, indicating that the stress accumulation of the Menyuan earthquake mainly took place before 2021. The b-value change of aftershock sequence in early stage can provide some reference for the location prediction of later aftershocks.

We use precise point positioning(PPP) technology to process the ground-based GNSS observation data of Guizhou to obtain high-precision zenith tropospheric delay(ZTD), and then carry out the water vapor inversion to obtain precipitable water vapor(PWV). Based on the slant-path water vapor(SWV), we use the adaptive simultaneous iterative reconstruction technique for 3D water vapor tomography, with spatial resolution better than 30 km×30 km, and time resolution of 5 min. The RMS is 3.55 mm and 1.03 mm respectively when the radiosonde data is used as a reference to evaluate the accuracy of ZTD and PWV. Using ERA5 reanalysis data as a reference to evaluate the accuracy of 3D water vapor tomography, the relative error is less than 10%, and the maximum deviation is 1.03 g/m³ when there is no rainstorm. Using radiosonde data as a reference to evaluate the accuracy of 3D water vapor tomography, the correlation coefficient between tomography results and radiosonde data is above 0.97, with good consistency. The average RMS of Guiyang station and Weining station is better than 0.5 g/m³ and 1.2 g/m³ respectively.

Since a single indicator or a simple combination of several indicators that cannot effectively characterize the  GNSS positioning quality, we propose a comprehensive evaluation indicator. This indicator normalizes the observation data quality indicators and GNSS positioning processing algorithm feature data, and uses the coefficient of variation weighting method to linearly combine several indicators. The new indicator is a comprehensive evaluation indicator, with smaller value indicating higher quality. The results show that the new indicator is an effective evaluation indicator for the positioning quality, which can be used in engineering practice and provide a new idea for the quality assessment of GNSS positioning.

Based on the quality analysis of raw GPS/BDS data of Xiaomi 8 smartphone, we propose a GPS/BDS positioning stochastic model combining elevation angle and signal-to-noise ratio. The results show that the positioning accuracy of the combined stochastic model is superior to that of the single factor stochastic model in the standard point positioning(SPP). In the single-frequency precise point positioning(PPP) solution model with additional ionospheric and tropospheric constraints, the positioning accuracy and convergence time of the combined model are better than that of the single factor stochastic model, and the positioning accuracy can converge to less than 1 m in 1 minute, the horizontal positioning accuracy is better than 0.5 m in 5 minutes. The positioning accuracy in horizontal direction and elevation direction is better than 0.2 m and 0.3 m, respectively.

On the basis of detailed analysis of the principle and steps of zero-difference kinematic precise orbit determination, we adopt the smooth Kalman filtering algorithm, and use self-developed precise orbit determination software for zero-difference kinematic precise orbit determination of GRACE-FO satellite. The results show that, compared with the official scientific orbits, the smooth Kalman filtering can not only improve the accuracy of orbit determination at the beginning stage, but also improve the accuracy of orbit determination on the whole. The corresponding orbit residuals of GRACE-FO C and GRACE-FO D satellites are 2-4 cm and 3-5 cm, respectively.

The traditional waveform retracking method cannot effectively process the noise of echo waveform of satellite altimeters in coastal areas, so we propose a new method of Jason-3 altimeter echo waveform retracking based on singular spectrum analysis to further improve the quality of waveform retracking data. Using singular spectrum analysis method, we filter the noise of echo waveform and extract the main waveform information. Then we carry out the waveform retracking processing. We retrack the raw waveform and filtered waveform, and compare and analyze the retracked sea surface height. The results show that the retracking method of Jason-3 altimeter echo waveform based on singular spectrum analysis is effective and reliable, which has a certain reference significance for further expanding the application of satellite altimetry technology in coastal areas.

The traditional receiver autonomous integrity monitoring(RAIM) algorithm carries out fault detection and identification based on least squares residuals method. Due to the ill-conditioned coefficient matrix problem of least squares residuals method, it may lead to missed detection and missed exclusion. Therefore, we propose an improved RAIM method based on internal coincidence accuracy. Based on the original fault detection method, this method introduces the test threshold of satellite positioning internal coincidence accuracy, and improves the traditional fault detection method to reduce the missed detection rate and improve the fault identification rate. The experimental results show that the improved method can effectively reduce the missed detection rate and efficiently identify faulty satellites without affecting the availability of system integrity algorithms. Compared to the missed detection rate of 4.66% and 1.95%  of the traditional algorithm in this experiment, the improved algorithm can reduce the missed detection rate to 2.21% and 0.81%.

We select the FES2004, NAO.99b, FES2014b, EOT20, GOT4.10c and TPXO9.5a ocean tide models for OTLD correction of 253 CMONOC GNSS stations, and analyze the influence of unmodeled or inaccurate OTLD on CMONOC GNSS coordinate time series and zenith troposphere delay(ZTD) estimation. The results show that the greater the influence of OTLD, the more obvious the improvement effect and difference of different tide model corrections on the wRMS of GNSS coordinate time series. The maximum improvement effect can be more than 52%, and the maximum difference can be up to 11%. The maximum amplitude of GNSS mixed signal caused by the difference of tide models is about 4 mm, and the corresponding periods are mainly 14.8 d and 365 d. There is a quasi-linear relationship between OTLD and ZTD deviation, and the better the practicability of tide model, the more obvious the linear relationship between them. FES2014b model has a better OTLD correction effect on the w_RMS of GNSS coordinate time series, the mixed period, and the ZTD estimation.

Taking the key subsidence area(north China plain) as the research area, we analyze the influence of incident angle difference, deformation reference point difference and atmospheric phase difference on InSAR monitoring results of multiple adjacent tracks. By introducing the quasi-stable datum adjustment method, comprehensively considering the leveling bedrock point, InSAR deformation reference point, CORS station and other factors to select quasi-stable points, we analyze the stability of InSAR monitoring results in the study area. We use the quasi-stable datum adjustment method to carry out the overall adjustment of time series InSAR monitoring results, and achieve the datum unification of vertical deformation field of large-scale multi-track InSAR. We check the internal coincidence accuracy of adjustment results based on the redundant observations in the overlap area of InSAR adjacent orbits. The average error after the quasi-stable datum adjustment is better than 5 mm, and the mean square error is better than 9 mm. We check the external coincidence accuracy of adjustment results based on the vertical displacement monitoring results of CORS stations, and the two are in good agreement.

In response to the demand for refinement and efficiency of microtremor survey in shallow urban areas, we design a rapid detection scheme for microtremor line array. Combined with practices, we design the output system of the fast detection scheme based on multiple coverage utilization of geophones and efficient-rolling observation of line array. This system is adopted in microtremor survey experiments from data acquisition to data processing at specific sites in urban areas. The results show that the scheme effectively enhance the efficiency of field observation and provide references for the rapid layout and translation of array.