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Using Geodesy to Understand Surface Process Hazards

Using Geodesy to Understand Surface Process Hazards. Geodesy is…. …the science of accurately measuring the Earth’ s size, shape, orientation, mass distribution and the variations of these with time. Traditional geodesy: Precise positioning of points on the surface of the Earth.

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Using Geodesy to Understand Surface Process Hazards

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  1. Using Geodesy to Understand Surface Process Hazards

  2. Geodesy is… …the science ofaccurately measuring the Earth’s size, shape, orientation, mass distribution and the variations of these with time. Traditional geodesy: Precise positioning of points on the surface of the Earth Modern geodesy: A toolbox of techniques to better measure the Earth wikipedia.org JPL/NASA 2

  3. Unpacking the Geodesy Toolbox • GPS (Global Positioning System) • InSAR (Interferometric synthetic aperture radar) • LiDAR (Light detecting and ranging) • Structure from Motion • Strain meters, tiltmeters, creep meters • Gravity measurements • Sea level altimetry • GPS (Global Positioning System) • InSAR (Interferometric synthetic aperture radar) • LiDAR(Light detecting and ranging) • Structure from Motion • Strain meters, tiltmeters, creep meters • Gravity measurements • Sea level altimetry usgs.gov http://photojournal.jpl.nasa.gov/catalog/PIA00557 www.jpl.nasa.gov http://facility.unavco.org/data/maps/GPSVelocityViewer/GPSVelocityViewer.html http://www.iris.edu/ http://www.nasa.gov/topics/earth/features/graceImg20091214.html

  4. High resolution topographic data can provide critical information about landslides

  5. Airborne Lidar

  6. Canopy Height (ft)

  7. Lidar’s ability to “see” through vegetation can help identify otherwise hidden landslides

  8. InSAR can provide critical rate information about creeping landslide movements

  9. use wave interference emit microwaves, measure echoes InSAR pretend you have a big radar antenna Interferometric Synthetic Aperture Radar

  10. SAR: how it works • Satellite emits radar pulse • Radar is backscattered • Amplitude and phase of echo recorded at the satellite

  11. InSAR: How it works Pass 1 Pass 2

  12. phase shift due to ground motion InSAR: How it works Pass 1: pre-movement Pass 2: post-movement phase=1 phase=2

  13. InSAR: How it works phase shift varies with distance from the fault

  14. InSAR can provide critical rate information about creeping landslide movements

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