More commonly seen in Greenland and West Antarctica, ice dolines are not widely known and therefore not frequently studied

Scientists around the world, debating over social media, have determined that an enormous crater in East Antarctica’s King Baudoin Ice Shelf, initially thought to be the result of a meteorite impact, is an ice doline — formed when meltwater lakes suddenly drain from below.

The crater was discovered by accident in December 2014 by a team of German scientists from the Alfred Wegener Institute (AWI). The scientists only intended to perform a short aerial survey of the bedrock surrounding Belgium’s Princess Elizabeth Station that day but instead decided to fly over the King Baudoin Ice Shelf, where they later spotted the crater.

“We were only flying that far in the north because the radar equipment had broken and we didn’t want to waste a good flying day,” explained Graeme Eagles, a scientist at the AWI, who is currently leading an Antarctic geophysical research survey at the station.

Cristian Müller, a geoscientist who was aboard the plane, described what he witnessed: “I looked out of the window, and I saw an unusual structure on the surface of the ice, there was some broken ice looking like icebergs, which is very unusual on a normally flat ice shelf, surrounded by a large, wing-shaped, circular structure.”

The crater is about two kilometres across, making it twice the size of Arizona’s Barringer Meteor Crater.

Müller and his team began searching scientific literature on Antarctica’s meteorite activity, as the crater bore structural details that did not rule out the theory that it could have been formed by a meteorite impact. At first, the crater was connected to a 2004 meteor blast detected above East Antarctica. However investigations later identified the crater in satellite images dating back to 1996, suggesting that the broken-up ice could be at least 25 years old. Researchers from the AWI, therefore, performed further observations with pictures, videos, laser altimeters and radar data mapping technologies, which plotted the crater’s contours in greater detail.

At the same time, scientists and researchers around the world were discussing the crater’s possible origins over social media, and eventually agreed that it was probably an ice doline — a sinkhole-type pit that is formed when meltwater lakes suddenly drain from below. Ice dolines are somewhat similar to sinkholes formed in limestone cave areas, however ice dolines tend to grow more rapidly than sinkholes due to the rapid drainage of water.

Ice dolines are more commonly seen in Greenland and West Antarctica due to frequent surface melting that results in the creation of scores of lakes, but even so, the phenomenon is not widely known.

A definite conclusion on whether the structure is an ice doline is expected in several months, following analysis of the extensive data collected by the AWI. Nevertheless, the hypothesis has raised many intriguing questions about the Antarctic continent and has demonstrated the power of social media to promote exciting scientific discoveries and include others in the scientific process.

— Antonio Sousa, Correspondent (Science)

Image Courtesy: Gregory “Slobirdr” Smith (https://www.flickr.com/photos/slobirdr/11010187683), Licensed under the Creative Commons Attribution-ShareAlike 2.0 Generic | Flickr