Detection of crevasses over polar ice shelves using Satellite Laser Altimeter

Ice shelf breakups account for most mass loss from the Antarctic Ice Sheet as the consequence of the propagation of crevasses (or rift) in response to stress. Thus there is a pressing need for detecting crevasses’ location and depth, to understand the mechanism of calving processes. This paper presents a method of crevasse detection using the ICESat-1/GLAS data. A case study was taken at the Amery Ice Shelf of Antarctica to verify the accuracy of geo-location and depth of crevasses detected. Moreover, based on the limited crevasse points, we developed a method to detect the peak stress points which can be used to track the location of the crack tips and to identify the possible high-risk area where an ice shelf begins to break up. The spatial and temporal distribution of crevasse depth and the spatial distribution of peak stress points of the Amery Ice Shelf were analyzed through 132 tracks in 16 campaign periods of ICESat-1/GLAS between 2003 and 2008. The results showed that the depth of the detected crevasse points ranged from 2 to 31.7 m, which were above the sea level; the crevasse that advected downstream to the front edge of an ice shelf has little possibility to directly result in breakups because the crevasse depth did not show any increasing trend over time; the local stress concentration is distributed mainly in the suture zones on the ice shelves.