L-Band InSAR for Detecting and Tracking Geohazards in Vegetated Areas

Previously unknown geohazards are a leading cause of failure of linear infrastructure. Detecting and monitoring geohazards over large infrastructure networks is subject to challenging tradeoffs between coverage, detail, and measurement frequency. Frequent regional scale monitoring with satellite radar interferometry (InSAR) can quickly identify and prioritize geohazards based on severity and proximity to infrastructure, facilitating field inspections and optimal deployment of limited in-situ instruments. We conducted an advanced InSAR analysis using long-wavelength ALOS-2 data to detect and measure geohazards over a 3,800 sq km sample footprint. The area is mostly vegetated hilly terrain in Ohio, West Virginia, and Pennsylvania necessitating the long 24 cm L-band wavelength of ALOS-2. L-band data is able to penetrate the canopy to measure the ground, which is not possible with shorter wavelength satellites. Many displacement areas were captured and quantified. The minimum detectable displacement rate was 2 cm per year. In addition to measuring linear displacement associated with landslides and subsidence, many transient non-linear displacement areas were also measured, including migrating subsidence areas associated with long-wall mining. By mapping the ratio between the displacement and the statistically derived noise, as both varied spatially and temporally, we highlighted signals that were statistically significant.

L-Band InSAR is demonstrated as an effective technology to support operational geohazard monitoring in vegetated terrain.