Land displacement monitoring (InSAR Ground Deformation Monitoring)

Geodetic monitoring is required in the following cases:

• During the construction, reconstruction, and restoration of buildings and structures;
• When using industrial, hydro, or energy technical facilities;
• When intervening in the geological or hydrological conditions of a site.

Geodetic monitoring is conducted during the construction of new structures or the restoration of existing ones to monitor settlement, deformation, and tilt. Permissible limits for these parameters are specified in construction codes, standards, regulations, and building rules. These limits should not be exceeded. The goal of geodetic monitoring is to track these values and prevent their exceedance.

Geodetic monitoring is performed throughout the year following the completion of construction or reconstruction works. During the observations, the following processes are monitored:

• Settlement - vertical displacement;
• Shifts - horizontal displacement;
• Tilts - deviations from the vertical.

This helps to prevent deformations, collapses, and other adverse events. If the changes do not stabilize, monitoring is extended and continued beyond the initial year.

• Regular monitoring of the current natural and man-made geodynamic state of the subsurface within the territory of deposits using modern high-tech equipment and efficient measurement techniques.
• Identification of patterns of occurrence and spatial-temporal development of various manifestations of natural and man-made subsurface geodynamics, including establishing the nature and mechanism of relationships between these manifestations and spatial-temporal changes in the parameters of deposit development. Conduct and systematically update the geodynamic zoning of the deposit territory (with necessary revisions as new geodynamic information is obtained), identifying potential areas of increased geodynamic risk within the deposit territory.
• Providing recommendations for optimizing the prospective placement of systems and facilities on the deposit territory to avoid potential emergency situations related to geodynamic factors.
• Systematically compile information and annual comprehensive reports with necessary attachments, recommendations, and programs for subsequent monitoring cycles.

• Quantitative assessment of the degree of modern activity of faults within the developed hydrocarbon deposit territory and adjacent areas, as well as the temporal changes in fault activity.
• Monitoring possible ground subsidence associated with deposit development (fluid extraction, reservoir pressure depletion) in the early stages of their development.
• Detection of local variations in gravity reflecting deformation processes and fluid dynamics within the geological environment occurring in the geological intervals, including potential compaction of reservoir rocks due to hydrocarbon extraction, temporal changes in reservoir pressure, and fluid withdrawal/injection balance.
• Identification of local areas with anomalous deformation processes and estimation of parameters of sources of local anomalous movements.
• Development of possible prognostic signs of hazardous geodynamic processes.
• Prediction of areas with increased geodynamic risk within the deposit territory.

Monitoring ground deformation involves using a combination of technologies and methods to accurately measure and analyze changes in the Earth's surface over time. Here are some of the most effective and commonly used techniques:

1. Global Positioning System (GPS)

• Method: High-precision GPS stations are installed at specific locations to provide continuous, real-time data on the position of these points.
• Advantages: High accuracy, real-time monitoring, suitable for long-term observation.
• Applications: Tectonic plate movements, earthquake prediction, monitoring infrastructure stability.

2. InSAR (Interferometric Synthetic Aperture Radar)

• Method: Satellite radar images of the Earth's surface are taken at different times and compared to detect changes in elevation.
• Advantages: Wide area coverage, high spatial resolution, can detect millimeter-scale changes.
• Applications: Volcanic monitoring, urban subsidence, landslide detection.

3. LiDAR (Light Detection and Ranging)

• Method: A laser scanner mounted on an aircraft or drone emits light pulses towards the ground, measuring the time it takes for the pulses to return to create high-resolution topographic maps.
• Advantages: High precision, can penetrate vegetation, useful for creating detailed surface models.
• Applications: Landslide monitoring, erosion studies, infrastructure monitoring.

4. Tiltmeters

• Method: Instruments that measure the tilt or inclination of the ground. They detect very small changes in the angle of the ground surface.
• Advantages: Sensitive to small changes, continuous monitoring.
• Applications: Volcanic activity, dam monitoring, slope stability analysis.

5. Strainmeters

• Method: Devices that measure the deformation (strain) in the Earth's crust by detecting changes in distance between two points.
• Advantages: High sensitivity to small strain changes, useful for detecting slow ground deformation.
• Applications: Earthquake research, tectonic studies.

6. Leveling Surveys

• Method: Traditional surveying technique where precise leveling instruments are used to measure vertical displacements.
• Advantages: High accuracy for vertical movements, cost-effective for small areas.
• Applications: Monitoring land subsidence, infrastructure stability.

7. Seismic Monitoring

• Method: Seismometers detect ground vibrations caused by seismic waves, which can indicate deformation.
• Advantages: Provides indirect evidence of deformation, useful for detecting deep-seated movements.
• Applications: Earthquake prediction, volcanic activity.

8. Photogrammetry

• Method: Using photographs taken from aircraft or drones to create 3D models of the terrain.
• Advantages: High spatial resolution, cost-effective for large areas.
• Applications: Landslide monitoring, coastal erosion studies, urban planning.

Implementation Steps for Ground Deformation Monitoring

1. Site Selection: Choose the areas to be monitored based on risk assessment, such as volcanic regions, earthquake-prone areas, or sites with significant human activities like mining.
2. Installation of Equipment: Install GPS stations, tiltmeters, strainmeters, or other necessary instruments in the selected area.
3. Data Acquisition: Collect data continuously or at regular intervals using the installed equipment.
4. Data Processing: Analyze the raw data to detect and quantify ground deformation. This may involve sophisticated algorithms and software tools.
5. Interpretation: Interpret the processed data to understand the underlying geological processes causing the deformation.
6. Reporting and Alerts: Provide reports and issue alerts if significant deformation is detected, which could indicate potential hazards.
7. Maintenance: Regularly maintain and calibrate the monitoring equipment to ensure data accuracy and reliability.

By combining these techniques and continuously monitoring the data, scientists and engineers can effectively track ground deformation, leading to better risk management and mitigation strategies.

Several tools and instruments are used to measure ground deformation, including:

1. GPS Stations: Provide continuous, real-time data on ground positions.
2. InSAR Satellites: Capture radar images to detect surface changes.
3. LiDAR Systems: Mounted on aircraft or drones for creating detailed terrain maps.
4. Tiltmeters: Detect changes in ground inclination.
5. Strainmeters: Measure the strain in the Earth's crust.
6. Leveling Instruments: Used in traditional surveys for vertical displacement.
7. Seismometers: Record ground vibrations.
8. Photogrammetry Software: Analyzes photographs to create 3D models.

Calculating deformation involves analyzing data from various instruments and applying mathematical and geospatial techniques:

1. Data Collection: Gather raw data from GPS, InSAR, LiDAR, etc.
2. Data Processing: Use software to process and correct data for errors.
3. Displacement Calculation: Determine changes in position or elevation by comparing data over time.
4. Strain and Stress Analysis: Calculate strain (deformation per unit length) and stress (force per unit area) using geophysical models.
5. 3D Modeling: Create visualizations and models to represent deformation.
6. Time-Series Analysis: Analyze changes over time to identify trends and patterns.

By integrating these steps, scientists can quantify and interpret ground deformation to understand its causes and implications.

Monitoring ground deformation using satellite technologies primarily involves radar-based and optical systems that provide high-resolution data over large areas. The key satellite-based techniques are Interferometric Synthetic Aperture Radar (InSAR) and, to a lesser extent, satellite optical imagery.

Interferometric Synthetic Aperture Radar (InSAR)

How InSAR Works:

1. Satellite Radar Imaging: Satellites equipped with radar sensors (e.g., Sentinel-1, TerraSAR-X) orbit the Earth and capture radar images of the surface.
2. Interferometry: By comparing radar images taken at different times from the same location, phase differences between the radar waves are analyzed.
3. Phase Difference Analysis: These phase differences correspond to changes in the distance between the satellite and the ground, which indicates ground displacement.
4. Displacement Maps: The processed data are used to create displacement maps showing vertical and horizontal movements of the ground.

Advantages of InSAR:

• Wide Area Coverage: Can monitor large regions, making it ideal for tracking deformation over vast areas.
• High Precision: Capable of detecting millimeter-scale changes.
• Repeatability: Frequent revisits by satellites allow for continuous monitoring.

Applications of InSAR:

• Volcanic Monitoring: Detecting ground deformation around volcanoes to predict eruptions.
• Urban Subsidence: Monitoring subsidence in cities due to groundwater extraction or construction activities.
• Earthquake Analysis: Assessing ground movements before and after earthquakes.
• Landslide Detection: Identifying areas at risk of landslides by tracking ground movements.

Satellite Optical Imagery

How Optical Imagery Works:

1. High-Resolution Images: Satellites (e.g., Landsat, Sentinel-2) capture high-resolution optical images of the Earth's surface.
2. Image Comparison: By comparing images taken at different times, changes in the landscape can be detected.
3. 3D Modeling: Using techniques like photogrammetry, 3D models of the terrain can be created to measure changes in elevation.

Advantages of Optical Imagery:

• Visual Analysis: Provides clear images that are easy to interpret visually.
• Broad Applications: Useful for various applications beyond deformation, like land cover change, agriculture, and urban planning.

Applications of Optical Imagery:

• Landslide Monitoring: Identifying and tracking landslide-prone areas.
• Coastal Erosion: Monitoring changes in coastline and erosion patterns.
• Urban Development: Tracking construction and land use changes in urban areas.

Combining InSAR and Optical Data

For comprehensive ground deformation monitoring, combining InSAR and optical data can provide a more complete picture. While InSAR offers precise measurements of displacement, optical imagery provides contextual information and visual confirmation of changes.

Steps for Combined Monitoring:

1. Data Acquisition: Collect radar and optical images from satellites over the area of interest.
2. Data Processing: Process radar images using interferometry to detect displacement and analyze optical images for visual changes.
3. Integration: Integrate both datasets to cross-validate findings and enhance the accuracy of deformation models.
4. Interpretation: Use the combined data to interpret the causes and implications of ground deformation accurately.

By leveraging satellite technologies like InSAR and optical imagery, scientists can effectively monitor and analyze ground deformation over large areas with high precision and frequency.