Flying over Antarctica’s Pine Island Glacier in a DC-8 research plane, scientists participating in NASA’s IceBridge mission made a startling discovery on October 14, 2011: a massive crack running about 29 kilometers (18 miles) across the glacier’s floating tongue. The rift was 80 meters (260 feet) wide on average, and 50 to 60 meters (165 to 195 feet) deep. It marks the moment of creation for a new iceberg that should eventually span about 880 square kilometers (340 square miles) once it breaks loose from the glacier.
… As a primary outlet for the West Antarctic Ice Sheet, the Pine Island Glacier is one of the largest sources of uncertainty in global sea level rise projections.
NASA Earth Observatory, “Birth of an Iceberg,” 3 November 2011