Researchers have proposed many theories about the Wilkes Land crater in East Antarctica since the 1960s. Only recently, though, have advances in research technology made it possible to see what’s behind this gravitational anomaly. New data suggest the subglacial hole may be an impact crater about 510 kilometers across, created by a meteorite strike. If confirmed, it would be the largest known impact crater on Earth.
Initially, researchers identified the feature as a massive dent in Earth’s gravity field. Early ground-based seismic and gravitational studies estimated the crater’s diameter at about 240 kilometers, but newer methods show it may be twice that size. In 2018, researchers found the structure lies roughly 1.6 kilometers beneath the Antarctic ice sheet, and they’ve been able to study the crater in greater detail than ever before. They’re also interested in a possible connection with southern Australia—Australia and East Antarctica were connected until about 35 million years ago. Although the crater’s origin isn’t certain, the evidence indicates the feature formed before the continents separated.
How did researchers land on a meteorite origin for the crater? They considered other possibilities, including a volcanic structure, a sedimentary basin, or a deeply eroded valley. In the latest study, researchers used satellite remote sensing to map the crater and measure its physical characteristics, as reported by Live Science.
Researchers think the crater’s central peak is a mass concentration, or mascon. Mascons form when an impact drives into Earth’s crust and disturbs the mantle beneath; after the impact, mantle rebound can create a dense plug that produces a positive gravitational anomaly. The Wilkes Land crater and its mascon aren’t perfectly circular—instead they form a U-shaped structure. New data show the northern side of the crater is fragmented, possibly because tectonic rifting separated Australia and Antarctica. Portions of the structure appear to be preserved in southern Australia.
Researchers also say the crater’s size is consistent with the size and velocity of objects that bombarded the young Earth between about 4.1 and 3.8 billion years ago. If the giant hole in East Antarctica is indeed an impact crater, it would be the largest known impact structure on the planet.
