GPS Stations Research Articles

ENGINEERING AND GEODESIC MONITORING OF DEFORMATIONS OF BUILDING STRUCTURES DAMAGED AS A RESULT OF MILITARY AGGRESSION

The problem of engineering and geodetic monitoring of damaged buildings as a result of Russian aggression is extremely relevant in today's environment. The importance of this issue for the construction industry is particularly high. The right approach to the engineering and geodetic monitoring of damaged buildings and structures will allow timely detection of deformation development and development of a stabilisation programme to help prevent future damage.There are many different methods for effective deformation monitoring, each with its own unique characteristics. Among them are standard methods such as geometric levelling and linear-angle measurements. Geometric levelling involves measuring the height differences between different points on an object, which allows you to accurately determine the change in the position of structural elements. Linear-angle measurements include measuring the lengths and angles between points, which helps to identify any changes in the geometry of the building.In addition to standard methods, automated observation methods are also actively used. These methods include the use of modern instruments and technologies that allow for continuous monitoring of deformations in real time. For example, automated total station surveys, GPS systems, laser scanners and other high-precision instruments allow data to be collected with high accuracy and speed.Automated monitoring significantly improves the efficiency and accuracy of observations of building deformations. The use of such systems allows for real-time data to be obtained, which is extremely important for timely response to any changes in the condition of facilities. This is particularly relevant in the context of post-war reconstruction, when the speed and accuracy of work are critical to ensuring the safety and stability of buildings.This article presents the results of engineering and geodetic monitoring of a residential complex on Zvirynetska Street. At this facility, geodetic works were carried out to measure the settlements and horizontal displacements of two sections.

Non-smooth Bayesian optimization in tuning scientific applications

Tuning algorithmic parameters to optimize the performance of large, complicated computational codes is an important problem involving finding the optima and identifying regimes defined by non-smooth boundaries in black-box functions. Within the Bayesian optimization framework, the Gaussian process surrogate model produces smooth mean functions, but functions in the tuning problem are often non-smooth, which is exacerbated by the fact that we usually have limited sequential samples from the black-box function. Motivated by these issues encountered in tuning, we propose a novel Gaussian process model called a clustered Gaussian process (cGP), where the components are dynamically updated by clustering. In our studies, the performance of cGP can be better than stationary GPs in nearly 90% of the experiments and better than non-stationary GPs in nearly 70% of the repeated experiments while requiring less computational cost. cGP provides a novel approach for dynamic GP, computes more efficiently than recursive partitioning, and discovers non-smoothness regimes. We provide extensive experiments including high-performance computing (HPC) and industrial simulation functions to show the effectiveness of our methods.

Analisis Deformasi di Lampung dan Selat Sunda berdasarkan Data GNSS tahun 2018 hingga 2021

The Lampung Province and Sunda Strait have a seismic gap zone with the potential for major earthquakes in the future. This study analyzes the deformation occurring in this region using continuous Global Navigation Satellite System (GNSS) station data from Indonesia Continuously Operating Reference Station (InaCORS) and Sumatran GPS Array (SuGAr) from 2018 to 2021.5. The GNSS data was processed using the Bernese 5.2 scientific software, applying least squares for velocity changes and statistical tests to analyze significance. The data processing was carried out in two schemes: the first scheme covering 2018-2020, and the second covering 2019-2021. The results of the deformation analysis from 2018 to 2021, using two continuous GNSS data processing schemes, showed velocity changes relative to the Sundaland Plate ranging from ~2 mm/year to ~20 mm/year. In the eastern region of the Sumatra fault, the velocity changes were smaller, around ~5 mm/year, due to the minimal influence of tectonic activity. However, in the Sunda Strait region, the deformation was influenced by volcanic activity. The deformation occurring in Lampung Province and the Sunda Strait, based on GNSS velocity changes, significantly contributes to tectonic and volcanic activities.

Assessment of Ground Control Points Positional Shift and Management Practices: Evidences from Assosa Town, Western Ethiopia

This study assesses the positional shift of existing control points and management practices found in and around Assosa town. The static GPS measurement technique was used as an independent source and a point wise method were used to assess the positional shift and accuracy level evaluation. Due to unavailability of local CORS station, two first order GCPs were used as a reference during static GPS measurement. After measurement was conducted depending on the baseline length between control point marks, the STC desktop software and online CSRS-PPP post processing technique was used. Thus, the positional accuracy of selected GCPs of STC Post processing technique has a mean error of 0.324 m and whereas the GCPs of CSRS-PPP has a mean error of 0.571 m. Horizontal distance error obtained with the STC differential technique is ranging from 0 to 0.83 m which is inconsistent relative to the range 0.437 m to 0.815 m obtained from online CSRS-PPP solution. The positional accuracy of GCPs was also assessed using horizontal distance error of both processed techniques. The positional accuracy of GCPs at 95% confidence level is between -0.117 m and 0.765 m with STC and between 0.395 m and 0.747 m in online CSRS-PPP solution. Based on the result, the accuracy level of existing GCPs found in Assosa town, does not meet the FGDC accuracy. This was mainly associated with perception of communities on ground control point management activities. The study revealed almost low communities practice and control point management responsiveness. Finally, study suggested that there should be participatory guidance to establish and manage the ground control points.

The effect of ambiguity resolution on the precision of the GPS/Galileo PPP using a u-blox ZED-F9P low-cost GNSS receiver

Thanks to the increasing number of low-cost dual-frequency GNSS receivers available on the market, the usability of these receivers for geodetic applications is increasing. Recently, PRIDE Lab at GNSS Research Center of Wuhan University has started to produce GNSS observable-specific phase biases for all-frequency. This enables precise point positioning with ambiguity resolution (PPP-AR) not only for conventional frequencies but also for other arbitrary frequencies. In this work, static and kinematic PPP-AR precision of the u-blox ZED-F9P low-cost GNSS receiver are investigated by comparing it with a geodetic-grade GNSS receiver using GPS-only, Galileo-only, and GPS + Galileo combinations for nearly two months period. Wide-lane (WL) and Narrow-lane (NL) AR fixing rates, cycle slips, code multipath, and frequency availability are also investigated for both receivers. In the positioning domain, GPS-only, Galileo-only, and GPS + Galileo PPP positioning precision using float ambiguities is significantly improved after AR for both receivers. GPS + Galileo PPP provides the best precision comparing with the other PPP solutions for both receivers using float and fix ambiguities. For static GPS + Galileo PPP-AR, the standard deviation of north, east, and up components are computed as 2.7/1.7/3.2 mm and 2.2/2.3/5.4 mm for the geodetic receiver and the u-blox receiver, respectively. The results also reveal that kinematic PPP-AR for the u-blox receiver is not as reliable as the geodetic-grade receiver yet suggesting potential for improvement in future iterations.

Accurate Deformation Retrieval of the 2023 Turkey–Syria Earthquakes Using Multi-Track InSAR Data and a Spatio-Temporal Correlation Analysis with the ICA Method

Multi-track synthetic aperture radar interferometry (InSAR) provides a good approach for the monitoring of long-term multi-dimensional earthquake deformation, including pre-, co-, and post-seismic data. However, the removal of atmospheric errors in both single- and multi-track InSAR data presents significant challenges. In this paper, a method of spatio-temporal correlation analysis using independent component analysis (ICA) is proposed, which can extract multi-track deformation components for the accurate retrieval of earthquake deformation time series. Sentinel-1 data covering the double earthquakes in Turkey and Syria in 2023 are used to demonstrate the effectiveness of the proposed method. The results show that co-seismic displacement in the east–west and up–down directions ranged from −114.7 cm to 82.8 cm and from −87.0 cm to 63.9 cm, respectively. Additionally, the deformation rates during the monitoring period ranged from −137.9 cm/year to 123.3 cm/year in the east–west direction and from −51.8 cm/year to 45.7 cm/year in the up–down direction. A comparative validation experiment was conducted using three GPS stations. Compared with the results of the original MSBAS method, the proposed method provides results that are smoother and closer to those of the GPS data, and the average optimization efficiency is 43.08% higher. The experiments demonstrated that the proposed method could provide accurate two-dimensional deformation time series for studying the pre-, co-, and post-earthquake events of the 2023 Turkey–Syria Earthquakes.

Makran Subduction Zone: A Review and Synthesis

This review synthesizes existing research to elucidate the factors driving the distinct tectonic behaviors in the western and eastern Makran subduction zone, focusing on seismic activity, uplift rate, convergence rate, coupling, and subduction angle. The literature identifies the asymmetry in pressure and the variation in subduction angles between the western and eastern parts of the Makran as key factors in defining the region’s tectonic patterns. The western region has a steeper subduction angle, resulting in lower pressure, reduced coupling, and decreased seismic activity. This disparity arises from different interactions between the subducted and overriding plates. This article offers an overview of the Makran subduction zone, identifies some knowledge gaps, and suggests directions for future research to improve our understanding of this complex geological region. The review highlights the need for more comprehensive GPS stations and targeted studies on subduction dip angles to better understand the region’s tectonic dynamics.

Synergistic use of SAR satellites with deep learning model interpolation for investigating of active landslides in Cuenca, Ecuador

Among the most intense geological disasters, landslides frequently occur throughout the world. These phenomena have been studied using space geodetic techniques, including Global Navigation Satellite Systems (GNSS) and Multi-Temporal Interferometric Synthetic Aperture Radars (MT-InSAR). Nevertheless, complete mapping and analysis of landslides’ surface deformation in most areas can be complicated due to a large diversity in kinematics, such as periods of quiescence and acceleration in the toe and crown. One of these landslides is the Cuenca landslides in Ecuador, where the geological investigation revealed that the toe of the landslides was located in urban areas, with more noticeable deformation effects. In contrast, its crown was located mainly in a rural and green land area. In this study, we show the potential of a synergistic use of COSMO-SkyMed (CSK) and Sentinel-1A (S1A) synthetic aperture radar (SAR) data for comprehensively monitoring the Cuenca landslides. To this aim, we have used Long-Short Term Memory (LSTM) and Convolutional Neural Networks (CNN) as two different Deep Learning Algorithms (DLAs) to integrate results in the temporal and spatial domain, respectively. A cross-comparison of the results was made with the nine GPS-derived deformations and the visual effects (i.e. crack width and pattern) on the field. This validation against GPS observation reveals that the RMSEs of the final MT-InSAR-derived velocity after applying the synergic double band SAR dataset decrease at more than 73% of nine GPS stations. Highlights Synergic MT-InSAR approach for studying landslide deformation in diverse kinematic areas. Utilized DLAs (LSTM and CNNs) for effective temporal and spatial interpolation of InSAR results. Findings emphasize the potential of multi-sensor SAR and DLAs for landslide monitoring regarding improving the RMSE at nine stations with an average of 73%.

Mapping vertical and horizonal deformation of the newly reclaimed third runway at Hong Kong International Airport with PAZ, COSMO-SkyMed, and Sentinel-1 SAR images

In order to meet long-term air transportation needs, Hong Kong International Airport (HKIA) has been constructing the third runway system (3RS) through land reclamation projects since 2016. However, the third runway and taxiway, which were paved in September 2021, suffered from severe surface settlement. Therefore, we attempted to reveal the settlement pattern within the 3RS and analyze the factors contributing to this displacement. Employing the multi-temporal interferometric synthetic aperture radar (MT-InSAR) technique, we utilized PAZ, COSMO-SkyMed, and Sentinel-1 satellite images to extract ground displacements along the radar line of sight. The results show that, compared with COSMO-SkyMed and Sentinel-1 images, PAZ demonstrates superior performance in the deformation monitoring of the HKIA, with more deformation details and larger displacements. The maximum settlement rate derived by PAZ on the 3RS exceeds 110 mm/year. To ensure the reliability of the derived displacements along the LOS, we validated them through cross-validation, comparing the outcomes from different SAR data with data from GPS stations. In order to gain a detailed deformation information, we derived the vertical and horizontal (ground range direction) displacements by utilizing deformation measurements along the LOS of multiple SAR satellites and the geometric information, and the maximum values recorded for vertical and E-W displacements reached 88.31 mm/y and 41.91 mm/y, respectively. Furthermore, our investigation revealed that the significant local deformation observed on the taxiway and third runway was predominantly attributed to various factors including the creep of soft soil, consolidation of filling materials, characteristics of road surface materials, and distinct stages of construction.

Surface deformation monitoring of Raniganj coalfield, India, using advanced InSAR and DGPS

The Raniganj coalfield, which is the oldest coal mine in India, is susceptible to ground subsidence. For the purpose of detecting surface deformation, this work makes use of field surveys, interferometric synthetic aperture radar (InSAR), and Differential GPS (DGPS). The study utilised Sentinel-1 InSAR data spanning from 2017 to 2023. PS-InSAR was used for both ascending and descending datasets, while SBAS-InSAR was used for descending datasets alone. Records show a maximum subsidence rate of −21.18 mm/year. Three surface deformation maps were generated from time-series assessments of individual locations, revealing regions undergoing significant changes. Known mining collapse locations and continuing deformation zones were designated with four differential GPS stations. By analysing the DGPS data with the GAMIT/GLOBK software, we were able to measure surfaces that were undergoing rapid deformation. Using Google Earth Engine (GEE), we generated thermal maps to delve deeper into the coal fire activity. We found coal bed methane (CBM) mining causing substantial subsidence in Kataberia and the surrounding areas. Shyamsundarpur and New Kenda are impacted by mining voids and coal fire-induced subsidence, respectively. The results of this study give the Raniganj region’s decision-making procedures more credibility in terms of minimising and controlling geological dangers.

Assessments of Land Subsidence in the Tehran Metropolitan Using Satellite Radar Interferometry Technique

Background and objective Many cities in the world have land subsidence problems because of environmental issues related to urban development. The arid and semi-arid climatic conditions prevailing in most of the interior regions of Iran and the need for the increasing industrial, agricultural, and drinking water exploitation from underground water resources, as well as urban development, have increased the occurrence of land subsidence in Iran, especially in the metropolis of Tehran. This study aims to assess land subsidence in Tehran, Iran, using the satellite radar interferometry (InSAR) technique. Method In this research, 31 images of Sentinel-1 were processed using the time series of persistent scatter interferometry (PSI) in 2022, and a map of the average annual rate of land subsidence in Tehran metropolis was prepared. Finally, after validating the results of interferometry with GPS station observations, the relationship between land subsidence and exploitation of underground water resources was examined as the most important factor in ground surface changes in the study area. Results The findings showed a decreasing trend in land subsidence from plain to urban areas. The highest land subsidence, with a rate of -43 mm per year occurred in the southern and southwestern parts of Tehran. Districts 10, 11, 12, 16, 17, 18, 19, and 20, which comprise about 26% of Tehran’s population, were experiencing land subsidence. The drop in the water level of observation wells was considerable in the areas where the highest rate of land subsidence occurred. Another finding of the research was the decrease of the underground water level from the north to the south of Tehran, indicating that the water depth in the southern areas of Tehran decreased due to human activities such as water pumping. Conclusion There is an increasing pressure in the aquifer through pumping water from wells in the study area for various industrial, agricultural and drinking water uses which has led to the increase in the occurrence of land subsidence.

Assessment of Mine Plans for Production and Variations at Ibese Limestone Mines

This research investigated the mine plans used for the production target and annual production of limestone for the past seven (7) years. The actual amount of limestone produced per year in tons was computed to determine the variations in the mine's production and the life span of the reserve of limestone deposits. A new mine plan was proposed, and a targeted amount of limestone production per year was suggested. The mine plans for the mine's production were generated from 2014 to 2020 using a complete data collection system for Real Time (RTK) GPS and Total Stations with in-field coordinate geometry called SurCE by Carlson Software. The total production target for the seven (7) years was 87,017,146 tons and the actual production was 76,313,056 tons. The total variations for the years under this assessment were -10,704,090 tons except for the year 2018 when the actual production was higher than the production target of 511,179 tons. The volumetric reserve estimation revealed that the total volume of the limestone reserve is 5,052,236,090.186 tons. The expected production per week was computed to be 356,400 tons/week, expected monthly production, (EMP) was estimated to be 1,425,600 tons/month. The expected production year, (EPY) was 17,107,200 tons/year and the life span of the limestone deposit, (LS) was computed to be 295.34 years. It can be suggested that the company should target a production rate of 1,425,200 monthly and 17,104,200 per year. This suggestion can be achieved if there is enough investment in terms of skilled labour, heavy-duty machinery, and equipment which will cost-effectively boost production.

Topographical Effects on Volcano Deformation Signal Intensity: Implications for GPS Network Configuration

AbstractVolcano GPS networks can capture vital information during volcanic unrest to aid with hazard assessment and eruption forecasting, but can be hindered by their discrete point locations and possibly miss key spatial information. We show how numerical models can reveal controls on spatial deformation signal intensity compared against GPS network design. Using the GPS network at Soufrière Hills Volcano (SHV), Montserrat, and a range of models, we explore expected surface deformation patterns. Peak horizontal deformation is located offshore, highlighting the difficulties with geodetic monitoring on small ocean‐island volcanoes. Onshore areas where the deformation signal is expected to be high are also identified. At SHV, topography plays a greater role in altering the relative distribution of surface displacement patterns than subsurface heterogeneity. Our method, which can be adapted for other volcanoes, highlights spatial areas that can be targeted for effective GPS station placement to help improve deformation monitoring efficiency.

Seismic effects at GPS stations: Case study of the 24 August 2016 Amatrice earthquake

Seismic effects at GPS stations: Case study of the 24 August 2016 Amatrice earthquake

Comprehensive analysis of the equatorial ionization anomaly based on global ionospheric maps with a high spatiotemporal resolution

The Equatorial Ionization Anomaly (EIA), a manifestation of Ionospheric plasma irregularities, is closely linked to the equatorial fountain, influenced by solar activity and Earth’s geomagnetic field. While previous studies on EIA have predominantly focused on specific regional analyses using TEC data from GPS stations, revealing correlations between peaks, discrepancies with models, and temporal variations, there exists a gap in comprehensive global statistics, consideration of different solar activity years, and exploration of EIA characteristics across various local time scales. To address these, this study employs high spatiotemporal data from the Global Ionospheric Map (GIM) to comprehensively analyze EIA across different periods of the day during high solar activity in 2014 and low solar activity in 2020. The study delves into the subtle variations of EIA under different solar activity levels and seasonal conditions, focusing on changes in occurrence rate, intensity, and geomagnetic latitude positions concerning longitude, month, and local time. Our study reveals several findings: (1) EIA exhibited more frequent and intense trends during high solar activity years, with higher occurrence rates and intensity observed during the equinoxes; (2) EIA exhibits significant variations across different longitudes and local times, showing systematic patterns in its occurrence rates over time; (3) The crest-to-trough TEC Ratio (CTR) effectively characterizes nighttime EIA intensity, while the crest-to-trough TEC Difference (CTD) is suitable for representing daytime EIA intensity; (4) The temporal changes in EIA positions may be related to electric fields and wind patterns, while differences in longitudes are attributed to variations in the geomagnetic field.

Monitoring the ionospheric conditions during the annular solar eclipse December 2019: A case study

This study investigates the ionospheric response to the December 26, 2019 annular solar eclipse over the southern tip of the Asia region, focusing on Malaysia, Sumatra, and Singapore. Utilizing data from GPS stations and ionosondes along the eclipse path, variations in Total Electron Content (TEC) and ionospheric foF2 parameters were analysed to assess the eclipse's impact. Results indicate a slight northward depletion of TEC, possibly linked to the Equatorial Ionization Anomaly (EIA), with up to −30% of depletions observed across all sites. Time delays in TEC and foF2 parameter responses suggest the influence of recombination and photochemical processes. Differences in depletion percentages between TEC and foF2 parameters may stem from production rate reductions during the eclipse. Post-sunset enhancements in TEC and foF2 parameters suggest the formation of ionospheric plasma blobs associated with Travelling Ionospheric Disturbances (TIDs) during the eclipse. While consistent with trends observed in prior studies, the study's findings highlight regional variations in ionospheric effects. This study enhances our understanding of ionospheric dynamics during solar eclipses and paves the way for further exploration in this area.

Constructing a Corrected Stations Network Using Some Geomatic Techniques

Abstract The major objective of this study is to establish a network of Ground Control Points-GCPs which can use it as a reference for any engineering project. Total Station (type: Nikon Nivo 5.C), Optical Level and Garmin Navigator GPS were used to perform traversing. Traversing measurement was achieved by using nine points covered the selected area irregularly. Near Civil Engineering Department at Baghdad University Al-jadiriya, an attempt has been made to assess the accuracy of GPS by comparing the data obtained from the Total Station. The average error of this method is 3.326 m with the highest coefficient of determination (R2) is 0.077 m observed in Northing. While in the Easting the average error is 4.634 m with (R2) 0.099 m observed. The average error 5.513 m with (R2) is 0.071 m is observed in Reduced Level. The accuracy assessments of the interpolation methods (Total Station and Level) have been calculated using the average error 0.240 m with (R2) is 0.735 m is observed in Reduced Level. The GIS 10.3 program can automatically transform the saved data to text format and produce digital plans with attribute.

Calculating of Taftan Volcano Displacement Using PSI Technique and Sentinel 1 Images

Abstract. Taftan is a semi-active volcano located in southeast of Iran with a number of craters. The main objective of this study is to investigate whether subsidence or uplift in Taftan peak. A total number of 58 images of Sentinel 1-A acquired between January 2015 to December 2020 in the ascending orbit mode and 102 images of both Sentinel 1-A, Sentinel 1-B acquired between October 2014 to June 2020 in the descending orbit mode were pre-processed for this purpose. The interferograms with the permanent scatterer interferometry (PSI) method were created using SARPROZ and StaMPS software in which atmospheric corrections were made automatically and following that get surface displacement of Taftan volcano. The results of the Line Of Sight (LOS) displacement corresponding to the uplift was observed to be 0.5 mm to 1 mm yr-1 for the ascending orbit and 1 mm yr-1 for the descending orbit. Because of GPS station lack close to Taftan volcano, the GPS measurements of one station located in the study area (Saravan station) was used to check the accuracy of PSI method, the GPS station of SARAVAN has been located inside of town and it is appropriate to use and analyze PSI technique in this station. As a result, it was found that the PSI method is in good agreement with the GPS data.

Registration of Interferometric DEM by Deep Artificial Neural Networks Using GPS Control Points’ Coordinates as Network Target

The Shuttle Radar Topography Mission (SRTM) satellite’s digital elevation model (DEM) is an important tool for studying topographic features on a medium-spacing scale. Data were collected and processed using the satellite’s orbital and navigation parameters with selected global GPS stations for verification. Distortion may be expressed by surveying measurements, such as position, distance, area, and shape. This study focuses on this distortion and proposes a new registration method to reduce its effect. Because of generality, the purpose shapes were excluded from this study. The proposed registration method depends on precise GPS control points that act as the ground truth for describing the considered surveying measurements. The processing was carried out using deep artificial neural networks (DANN) to produce a new registered DEM. A comparison was made between the original DEM and the new one, focusing on the selected surveying measurements. Another comparison was made between the GPS coordinates and SRTM polynomials to determine the potential of the proposed system. Some statistical investigations were applied to determine the level of significance of the distortion in each surveying measurement. The study shows that the distortion is highly significant; therefore, the proposed registration method is recommended to fix the distortion.

TEC disturbances caused by CME-triggered geomagnetic storm of September 6–9, 2017

This study investigates the ionospheric response to a geomagnetic storm triggered by a Coronal Mass Ejection (CME) during 6–9 September 2017, across GPS stations located in diverse geographical regions. We analyze the changes in the magnetic field component (ΔH), the Prompt Penetration Electric Fields (PPEF), and the Total Electron Content (TEC). We find that ΔH exhibits latitude-dependent responses during the storm, with high-latitude stations experiencing more significant reductions compared to low-latitude stations. The PPEF behavior is found to be directly correlated with solar wind disturbances. Particularly during the main phase of the storm, fluctuations in PPEF were clearly associated with negative values in the Dst index. The KIRU station, located at a high latitude, shows the most pronounced PPEF effects, indicating the increased susceptibility of high-latitude regions to solar wind interactions. The time series plot of TEC, covering a full month at different stations, shows a distinct diurnal pattern driven by solar ionization. Equatorial stations such as HYDE, BOU, HON (HNLC), and DODM exhibit the highest daily TEC values. During the geomagnetic storm, TEC disturbances are evident across all stations, with significant disturbances and varying trends in TEC depletion rate observed at different locations. The TEC values differ by 5–25 TECU during the storm period, suggesting intricate ionospheric responses to geomagnetic storms at different stations. This highlights the importance of considering different geographical regions to fully understand the ionospheric dynamics related to solar activities.