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.

本数据集发布包含4个地理信息系统（Geographic Information System, GIS）形状文件（shapefile）、1个Google Earth KMZ文件，以及5份元数据文件，汇总了针对阿拉斯加冰川湾地区与不列颠哥伦比亚省开展的合成孔径雷达干涉测量（Interferometric Synthetic Aperture Radar, InSAR）分析结果。核心形状文件（Moving_Ground）与KMZ文件（GBRegionMovingGround）内含多边形要素，用于勾勒该区域内移动速率处于雷达视线方向0.5~6厘米/年的低速滑坡与沉降冰水扇三角洲。滑坡与扇三角洲的识别依据，为哨兵-1（Sentinel-1）C波段合成孔径雷达影像的干涉图所捕获的位移信号。该影像于2018年至2020年的6月至10月期间，以12天为间隔获取。研究团队针对降轨（轨道P145）与升轨（轨道P50）两组卫星轨道的影像，采用永久散射体合成孔径雷达干涉测量（Persistent Scatterer InSAR, PSInSAR）方法开展处理。研究以降轨轨道的PSInSAR分析结果作为识别地表运动的核心依据，并借助升轨轨道的分析结果对地表运动信号进行验证。两组影像的重叠覆盖区域面积达14780平方千米，展示于本页面右侧的地图中。Moving_Ground形状文件与GBRegionMovingGround KMZ文件中的每个多边形，均勾勒出2018年至2020年期间存在地表运动的区域范围。研究团队将每一处地表运动区域划分为以下三类：1）远离现今冰川末端（距离＞2千米）的陡峭岩质斜坡低速滑坡；2）紧邻现今冰川末端（距离＜2千米）、与冰川变薄及退缩过程相关的低速滑坡；3）冰川末端附近的冰水扇三角洲沉降。上述三类地表运动类型，在Moving_Ground形状文件的属性表，以及GBRegionMovingGround KMZ文件的说明框中均有明确区分。属性表同时提供了每个多边形的面积（单位：平方米）。总体而言，研究共探测到4处远离冰川末端的滑坡、22处紧邻冰川末端的滑坡，以及5处发生沉降的冰水扇三角洲。本发布包中的其余3个形状文件分别为：冰川湾国家公园与保护区边界文件（Park_Boundaries）；轨道P145与P50的卫星覆盖区域及两者重叠范围文件（Satellite_Coverage）；以及Moving_Ground形状文件中各多边形的点位与标注文件（Movement_Locations）。本数据集已应用于下述已投稿待刊的学术论文：Kim J、Coe J A、Lu Z、Avdievitch N N、Hults C P，《阿拉斯加与不列颠哥伦比亚省冰川湾国家公园及周边快速冰退区域的星载InSAR滑坡与沉降制图》，《环境遥感》（Remote Sensing of Environment）。