Landslide-Wide Kinematics Revealed by Combining Interferometric Synthetic Aperture Radar and Continuous GPS Observations
Delbridge, Brent1; Roland, Bürgmann1; Eric, Fielding2; Gurrola, Eric2; Hensley, Scott2; Schulz, Bill2
1University of California Berkeley, UNITED STATES; 2Jet Propulsion Laboratory, California Institute of Technology, UNITED STATES
This project focuses on improving the understanding of the physical mechanisms controlling landslide motion by studying the landslide-wide kinematics of the Slumgullion landslide in southwestern Colorado using interferometric synthetic aperture radar (InSAR) and GPS. The Slumgullion landslide provides an ideal setting in which to study landslide mechanics because of its rapid deformation rates of up to 2cm/day and the large spatial extent in which to examine the complex interactions of different kinematic elements within the slide.
The NASA/JPL UAVSAR airborne repeat-pass SAR interferometry system imaged the Slumgullion landslide from 4 look directions on eight flights in 2011 and 2012. Combining the four look directions allows us to extract the full 3-D velocity field of the surface. COSMO-SkyMed(CSK) high-resolution Spotlight data was also acquired during time intervals overlapping with the UAVSAR one-week pairs, with intervals as short as one day. Interferograms made from pairs of CSK images acquired in 2010, 2011 and 2012 reveal the slide deformation on a longer timescale by allowing us to measure meters of motion and see the average rates over a year intervals using pixel offset tracking of the high-resolution SAR amplitude images. Additionally, TerraSAR-X data repeat-pass interferometry data was acquired in 2011-2012 and TanDEM-X bistatic (single-pass interferometry) data was acquired in 2011. The TanDEM-X bistatic data will enable construction of a high-resolution InSAR DEM.
The ultimate goal of this project is to use the kinematic information provided by these various geodetic methods along with in situ measurements to determine the physical mechanisms controlling landslide motion. By utilizing the temporal resolution of real-time GPS we acquired during a temporary deployment from July 22nd - August 2nd with the landslide-wide coverage of the InSAR-derived deformation, we hope to elucidate the response of the landslide to environmental changes such as rainfall, snowmelt, and atmospheric pressure, and consequently the mechanisms controlling the dynamics of the system.
The results of this study will also allow us to test the agreement and commensurability of UAVSAR-derived deformation with real-time GPS observations and traditional satellite-based SAR interferometry from the COSMOSkyMed system. We will not only help mitigate the hazards associated with large landslides, but also provide information on the limitations of current geodetic imaging techniques. This unique opportunity to compare several concurrent geodetic observations of the same deformation will provide constraints and recommendations for the design and implementation of future geodetic systems for the monitoring of Earth surface processes.