Although the answer to this question seems like it should be easy and straightforward, it is actually quite complicated and not straightforward at all. The short answer is that the Vredefort crater is the largest verified asteroid crater in the world. However, the Wilkes Land crater may be larger but it has not been verified, yet.
The Vredefort crater was approximately 186 miles (300 km) in diameter, 3 miles (5 km) deep, and around 2 billion years old. It is located in South Africa’s Free State Province. Today, due to erosion, most of the rim is no longer in place. However, there is a visual ring that can be seen from space that is approximately 24 - 56 miles (40 – 90 km) in diameter.
The rock that was turned up originates from layers nearly 12.5 miles (20 km) under the Earth’s surface. There is also a dome located in the center of the asteroid crater. In fact, researchers originally believed that the dome was created from the release of a volcano. In the 1990s, the researches discovered that it was due to an asteroid impact. The Vredefort asteroid crater is one of the rare sites where there are multiple rings showing the impact of the asteroid. However, many of the rings have been destroyed through erosion and earthquakes.
If it can be verified, the Wilkes Land asteroid crater would be even larger than the Vredefort asteroid crater. It is expected to be 300 miles (500 km) in diameter and is located in Wilkes Land, Antarctica. However, it is located over one mile (1.6 km) under a sheet of ice, so samples are not available for testing, at this time.
Researchers, Ralph von Frese and Laramie Potts, saw tell-tale signs that an asteroid crater is present. These signs include the existence of a mass concentration and larger rings radiating from its center. The mass concentration was spotted when NASA’s GRACE satellites were used to compare density differences in gravity measurements. Then, the rings were found using radar topography.
Researchers also believe that the Wilkes Land asteroid crater is not even 500 million years old. Some are studying whether the impact of the asteroid and the creation of the asteroid crater caused separation of Australia from the supercontinent Gondwana because it weakened the earth’s crust in that area. Other researchers are looking for other reasons behind the mass and the rings at the proposed Wilkes Land asteroid crater site. These explanations include volcanic activity on the largest scale.
Until samples are tested to verify whether it is indeed an asteroid crater, researchers will continue to wonder. NASA funded the original Wilkes Land discovery. In the meantime, Vredefort crater still reigns supreme.