Landsat Tracks Brunt Ice Shelf Evolution 1986-2023

Geolocated Landsat images show changes to this remote ice shelf in East Antarctica from 1986 to 2023, including rifting leading up to, during, and after major calving events in February 2021 and January 2023.

Although imagery acquisition was limited from 1986 to 2012, annual views of the ice shelf and its developing major rifts were possible following the launch of Landsat 8 in February 2013.

Reactivation of Chasm-1 in 2012 was followed by the rapidly extending ‘Halloween Crack’ in 2016 and the ‘new’ crack in 2020. The new crack was the first to release a major iceberg in 2021 (Iceberg A-74, 1270 km^2, ~490 mi²). The Halloween Crack ends in the mélange of the Brunt Basin as of early in 2023 but could calve in the near future. The MacDonald Ice Rumples are a submarine bedrock knob that has helped stabilize this ice shelf since Ernest Shackleton's Imperial Trans-Antarctic Expedition mapped this vicinity in January 1915.

Although necessarily repositioned through the decades (the 1^st base was built in 1956), The British Antarctic Survey’s (BAS) Halley Research Station (red H# on imagery) was moved beyond Chasm-1 well before the larger calving took place in January 2023 (Iceberg A-81, 1550 km², ~600 mi²).

Both Iceberg A-74 and A-81 are currently moving on the Weddell Sea’s gyre, a portion of overall Southern Ocean circulation around Antarctica.

See the following sources:

• Brunt Ice Shelf in Antarctica calves giant iceberg (British Antarctic Survey)
• History of Halley (Station Z)
• Breakup at Brunt (Iceberg A-74, 1270 km2, ~490 mi2, 27 February 2021)
• Antarctic Iceberg on the Move (Iceberg A-81, 1550 km2, ~600 mi2, 22 January 2023