FIELD VERIFICATION OF SATELLITE-BASED VELOCITY DATA

Interferometric synthetic aperture radar (InSAR) has become a popular satellite-based remote sensing technique used to measure many types of ground deformation, including subsidence/uplift, faulting, and landslides. InSAR stacking, such as the persistent scatterer interferometry (PSI) algorithm, allows for pixel-scale velocity measurements as accurate as 1 mm/year. The purpose of this project is to assess the capabilities of PSI to identify hazard zones through field verification and validation.

The study area is a 30-km railroad corridor that traverses a canyon system composed of volcanic sediments and rocks in southeastern Nevada. Since 2005, sporadic rockfalls have occurred along slopes near the railroad tracks, prompting an investigation of the capabilities of various remote sensing techniques to monitor slope movements and to identify additional, potentially unstable regions. With the use of PSI a total of 90 satellite images (ERS-1/-2 and ENVISAT), acquired over the railroad corridor from 1992 to 2011, were processed and results are in the form of persistent scatterer (PS) points.

Potential hazard zones were identified using qualitative criteria similar to those found in current slope management programs. Slopes were classified as hazardous if they displayed the following three criteria: (1) slope height 50 feet, (2) located within 100 feet of railroad tracks, and (3) average downslope velocity > 2 mm/year. 13 potential hazard zones were identified. This presentation will discuss the capability of radar interferometry, coupled with basic slope management criteria, to accurately identify downslope movements along a transportation environment. Field verification will help solidify the benefits of utilizing InSAR techniques.