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Science for a changing world.
Massive Iceberg on the Loose.
Image of the Week.
The world's largest iceberg floats freely in the Southern Ocean.
Iceberg A23a is a 1,500 square mile ice mass
larger than the state of Rhode Island.
A23a weighs approximately 1 trillion tons and measures
around 1,300 feet thick.
A23a began
its journey in August 1986, when it calved,
or broke off, from Antarctica's Filchner Ice Shelf.
The iceberg remained grounded on the seafloor
in the Weddell Sea for the next three decades.
In 2020, A23a detached from the seabed and began drifting north.
For the next four years, the iceberg followed the Antarctic
Circumpolar Current on a path known as Iceberg Alley.
Around April 2024.
A23a became trapped in an ocean vortex—a Taylor Column—
near the South Orkney Islands.
In Taylor Columns, currents
flowing around underwater mountains create rotating columns of water.
A23a began spinning counterclockwise about 15 degrees
every day, trapped in a swirling vortex for eight months.
December 2024, A23a broke free
from the Taylor column and is drifting north in the Southern Ocean.
The iceberg could collide with South Georgia, an island
in the South Atlantic Ocean.
Although the iceberg escaped one fate.
A23a now floats towards its probable demise;
if the iceberg doesn't hit South Georgia, the British Antarctic Survey predicts
A23a will likely split into smaller icebergs and meet a watery
grave in the warmer currents of the north.
Landsat images help scientists study icebergs and other surface
phenomena, as well
as indirectly reveal geological features beneath the ocean through observations,
such as those of sediment plumes and changes in ocean color.
Credits and sources appear on screen.
USGS Science for a changing world.