Quantifying Measurement Capabilities of Ground-Based Interferometric Radar for Rockfall Hazard Applications

New ground-based remote sensing techniques developed over the past decade present solutions to many challenges associated with traditional in situ monitoring of mass movement hazards. In particular, ground-based interferometric radar (GBIR) and terrestrial laser scanners (TLSs) are ideal candidates for application to rockfall hazard monitoring, owing to high precision in displacement sensitivity and spatial resolution, respectively. Through controlled experiments with a synthetic rock specimen and measurements of induced rock movements in the field, this study aims to quantify lower bounds of repeatable displacement detection for single rock targets using GBIR and to compare the results to total station and TLS measurements. One investigation used a synthetic rock that was moved with precisely controlled displacements to determine the lower bound threshold and accuracy of the GBIR for detecting translational movements of a realistic rock-like scatterer. This study found that the GBIR system was capable of reliably measuring displacements as low as about 0.2 mm with accuracy in the range of 0.1 to 0.2 mm. A controlled study was also performed at a field site where boulders were displaced at millimeter-scale increments and measured using the GBIR, a total station, and a TLS. Results from this portion of the study showed consistent results between the three measurement techniques within measurement error bounds.