Slow-moving landslides and subsiding fan deltas mapped from Sentinel-1 InSAR in the Glacier Bay region, Alaska and British Columbia, 2018-2020

This data release contains four GIS shapefiles, one Google Earth kmz file, and five metadata files that summarize results from Interferometric Synthetic Aperture Radar (InSAR) analyses in the Glacier Bay region of Alaska and British Columbia. The principal shapefile (Moving_Ground) and the kmz file (GBRegionMovingGround) contain polygons delineating slow-moving (0.5-6 cm/year in the radar line-of-sight direction) landslides and subsiding fan deltas in the region. Landslides and fan deltas were identified from displacement signals captured by InSAR interferograms of Sentinel-1 C-band Synthetic Aperture Radar images. The images were acquired at 12-day intervals from June to October from 2018 to 2020. We applied the persistent scatterer InSAR (PSInSAR) methods to images from both descending (scene P145) and ascending (scene P50) satellite tracks. We used PSInSAR results from the descending track as a primary means to identify ground movement and then used results from the ascending track to confirm the ground movement. The overlapping area covered by both images is 14,780 sq. km and is shown on the map at the right-hand side of this page. Each polygon in the Moving_Ground and GBRegionMovingGround files outlines an area of moving ground from 2018 to 2020. We categorized each area of moving ground into one of three categories: 1) slow-moving landslides on steep rocky slopes not near (> 2 km away from) present-day glacier termini, 2) slow moving landslides directly adjacent to (< 2 km away from) and associated with glacier thinning and retreat; and 3) subsidence of outwash fan deltas near glacier termini. These three categories are differentiated in the Moving_Ground shapefile attribute table and in an explanation box in the GBRegionMovingGround kmz file. The attribute table also provides the area of each polygon in sq. meters. Overall, we detected 4 landslides distal to glacier termini, 22 adjacent to termini, and 5 subsiding fan deltas. The other three shapefiles included in this release contain: the boundaries of Glacier Bay National Park and Preserve (Park_Boundaries); the coverage area for scenes P145 and P50, and the overlap between the two (Satellite_Coverage); and points and labels for each polygon in the Moving_Ground shapefile (Movement_Locations). These data were used in the following interpretive paper: Kim, J., Coe, J.A., Lu, Z., Avdievitch, N.N., and Hults, C.P., in review, Spaceborne InSAR mapping of landslides and subsidence in rapidly deglaciating terrain, Glacier Bay National Park and Preserve and vicinity, Alaska and British Columbia: Remote Sensing of Environment.