3D decomposition of InSAR LOS velocities of Thompson River Valley's landslides

Introduction

This tutorial provides a comprehensive guide on performing a 3D decomposition of InSAR (Interferometric Synthetic Aperture Radar) line-of-sight (LOS) velocities, specifically focusing on the landslides in the Thompson River Valley. The techniques discussed are relevant for those interested in geotechnical engineering, remote sensing, and landslide analysis.

Step 1: Understand InSAR and LOS Velocities

• What is InSAR?

  • InSAR is a remote sensing technique used to measure ground deformation by analyzing radar signals from satellites.

• Understanding LOS Velocities

  • LOS velocities refer to the speed and direction of ground movement as measured along the line of sight from the radar to the ground surface.

• Relevance

  • This technique is crucial for monitoring landslides, as it provides precise measurements of ground movement over time.

Step 2: Data Acquisition

• Identify Data Sources

  • Obtain InSAR data from satellite missions such as Sentinel-1 or ALOS. These sources provide the necessary radar images for analysis.

• Download Required Data

  • Access the data through platforms like Copernicus Open Access Hub or UNAVCO.
  • Ensure you have images from multiple time points to analyze movement effectively.

Step 3: Preprocessing Data

• Image Alignment

  • Align the radar images to correct for any discrepancies in satellite positioning.

• Interferogram Generation

  • Create interferograms using pairs of radar images. This step involves:
    • Subtracting the phase of the reference image from the phase of the target image.

• Filtering

  • Apply filtering techniques to enhance the quality of the interferograms and reduce noise.

Step 4: Decomposition of LOS Velocities

• 3D Decomposition Techniques

  • Utilize methods such as the Singular Value Decomposition (SVD) to break down the LOS velocities into three-dimensional components.

• Mathematical Formulation

  • The decomposition can be represented mathematically to separate horizontal and vertical movements:
    • Use equations that relate LOS measurements to vertical and horizontal components.

• Practical Tip

  • Ensure that you have a solid understanding of linear algebra as it plays a crucial role in the decomposition process.

Step 5: Analyze Results

• Visualize Data

  • Use software tools like MATLAB or Python libraries (e.g., Matplotlib) to visualize the decomposed 3D velocities.

• Interpret Findings

  • Analyze the results to identify patterns in the landslide movements. Look for:
    • Areas with significant vertical displacement.
    • Correlation between horizontal movement and geological features.

Step 6: Validate Findings

• Field Verification

  • Conduct field studies to validate the InSAR results. Use GPS or other ground-based measurement tools to compare with the InSAR data.

• Adjust Models

  • If discrepancies are found, adjust your models or analysis methods accordingly to improve accuracy.

Conclusion

In this tutorial, we explored the process of 3D decomposition of InSAR LOS velocities for analyzing landslides in the Thompson River Valley. Key steps included understanding InSAR, data acquisition, preprocessing, decomposition, result analysis, and validation. By following these steps, you can effectively monitor and analyze landslides using advanced remote sensing techniques. For further exploration, consider diving deeper into specific software tools or advanced mathematical techniques used in this field.