Abstract
On 26 September 2019, a massive iceberg broke off the west side of the Amery Ice Shelf (AIS) in East Antarctica. Since 1973, the AIS calving front has steadily advanced at a rate of 1.0 km yr−1. However, the advancement rate of the central portion of the AIS increased dramatically during 2012–2015, which indicates a velocity increase prior to the calving event. Eight calving front locations from 1973 to 2018 were mapped to investigate the advancement rate of AIS over the entire observational period. Additionally, the propagation of rift A was observed unstable from 2012 to 2015. The westward propagation rate of rift A1 increased to 3.7 km yr−1 from 2015 to 2017, which was considerably faster than the other rifts near the AIS calving front. The increased advancement rate and the increasing propagation magnitude of at least one active rift appear to be precursors of this large calving event.
Highlights
Iceberg calving, followed by basal melting, is the primary cause of mass loss of the Antarctic Ice Sheet
The westward propagation rate of rift A1 increased to 3.7 km yr−1 from 2015 to 2017, which was considerably faster than the other rifts near the Amery Ice Shelf (AIS) calving front
Nine cross-sections were created paralleling the dominate flowlines along each calving front position (Figure 1) which divided the AIS calving front into three portions: eastern, central, and western
Summary
Iceberg calving, followed by basal melting, is the primary cause of mass loss of the Antarctic Ice Sheet. Alley et al revealed that iceberg calving increases with the along flow spreading rate of an ice shelf [4]. Significant ice front advancement can be an important indicator for potential iceberg calving events. Most of the calving occurs at the front of ice shelves along the rift fractures that extend through the total thickness of the ice. most of the calving occurs at the front of ice shelves along the rift fractures that extend through the total thickness of the ice These ice-shelf rifts can propagate horizontally over decades before a significant iceberg calving event [5]. The characterization of the propagation of rifts on ice shelves plays an important role in understanding their ice stability and the influence of flow dynamics on ice-shelf calving
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