InSAR characterization of short-term deformation in a Late Quaternary landslide complex in the lower Rio Grande Gorge, New Mexico, U.S.A.

In northern New Mexico, the Rio Grande has carved gorges through structural transfer zones and volcanic edifices of the Rio Grande Rift, triggering adjacent hillslope adjustments via large, deep-seated landslide complexes. At White Rock Canyon, such landslides formed lakes that temporarily flooded the Española Basin during the latest Pleistocene. A similar landslide complex exists upstream adjacent to the Rio Grande on Black Mesa's eastern slope between Española and Taos. This study aims to identify the present-day instability in Black Mesa's landslide complexe in the context of its long-term topographic evolution. Utilizing Interferometric Synthetic Aperture Radar (InSAR) time series of Sentinel-1 data from 2017 to 2023, Spatial Kolmogorov-Smirnov (SKS) analysis, and LiDAR-derived topographic roughness, a comprehensive analysis was conducted. InSAR reveals significant movement of these landslides, with subsidence exceeding 40 mm over seven years. The landslides' lower portions (toes) exhibit higher deformational activity than the upper portions (crowns). Topographic roughness is considerably higher near the crowns due to secondary scarps from past landslide activity. The SKS analysis shows a statistically significant relationship between topographic closed depressions and their proximity to secondary scarps, implying a control of landslide activity on the spatial distribution of these features. These results underscore the interplay of long-term and modern processes shaping landslide dynamics, with crowns dominated by tensile fractures moving at different rates than toes, which are influenced by contemporary geological agents.