| Summary: | Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 48(3), (2021): e2020GL091200, doi:10.1029/2020GL091200. Tabular calving events occur from Antarctica's large ice shelves only every few decades, and are preceded by rift propagation. We used high-resolution imagery and ICESat-2 data to determine the propagation rates for the three active rifts on Amery Ice Shelf (AIS; T1, T2, and E3) and observe the calving of D-28 on September 25, 2019 along T1. AIS front advance accelerated downstream of T1 in the years before calving, possibly increasing stress at the rift tip. T1 experienced significant acceleration for 12 days before calving, coinciding with a jump in propagation of E3. ICESat-2's high resolution and repeat acquisitions every 91 days allowed for analysis of the ice front before and after calving, and rift detection where it was not visible in imagery as a ∼1 m surface depression, suggesting that it propagates as a basal fracture. Our results show that ICESat-2 can provide process-scale information about iceberg calving. We received funding from the following sources: NASA NNX15AC80G and NSF grant 1443677 (Fricker and Becker) and NASA 80NSSC20K0960 (Walker). We are grateful to Mike Cloutier, Polar Geospatial Center for assistance with WorldView imagery. Geospatial support was provided by Polar Geospatial Center under NSF-OPP awards 1043681 and 1559691. 2021-07-12
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