Possible Antartic Impact Field

Researchers find possible impact field in Antartica

Sept 1, 2004 Geophysicists John Weihaupt of the University of Colorado at Denver and Frans van der Hoeven of Delft University of Technology say they have found an impact crater field in Antartica. The pair sifted through gravity data collected from the Champs EIGEN-IS satellite and have identified gravity anomalies in Antartica.

The Champs program uses a single satellite to measure gravity field changes. The satellite's orbit fluctuates as it orbits the earth, moving higher in regions where earth's gravity is weak and lower where it's stronger. The satellite can locate its position relative to the earth to within a few centimeters by acquiring GPS signals from 12 GPS satellites simultaneously.

The technique varies from the technique used by by David Sandwell, et al. wherein they measure the elevation of the ocean's surface to deduce variations in the earth's gravity.

Dr's Weihaupt and van der Hoeven's press release reads:

Press Release Draft


(J.G. Weihaupt and F.G. van der Hoeven)

An international scientific-mountaineering team has discovered what appears to be one of the world’s largest meteoroid impact craters. Located in Victoria Land, Antarctica beneath more than two thousand meters (6000 feet) of ice, the subglacial topographic feature, discovered using field gravity survey techniques, is a minimum of two hundred and forty kilometers (144 miles) in diameter. Geophysicists John Weihaupt of the University of Colorado at Denver and Frans van der Hoeven of Delft University of Technology, discoverers of the impact crater, have recently expanded their investigation on the basis of satellite remote sensing gravity data collected by scientists from the Champs GPS, EIGEN-IS Project in Potsdam, Germany. These data reveal a continent-wide negative gravity anomaly field of numerous very large negative gravity anomalies in the Ross Sea in the vicinity of the Pacific Ocean, in central East Antarctica, and extending to the Weddell Sea adjacent to the Atlantic Ocean. While most of these gravity anomaly sites lie beneath the East Antarctic continental ice sheet, and are not presently accessible to direct observation, those offshore beneath the Ross and Weddell Seas are likely to be accessible to future direct observation from oceanographic research platforms.

Dr. Weihaupt and Dr. van der Hoeven, who presented their results at the 32nd International Geological Congress conference in Florence, Italy, August 24th, have shown that the shape and distribution of the huge Antarctic negative gravity anomaly field is identical to virtually all other multiple meteoroid impact fields on Earth. Known as scatter ellipses, scatter ellipses such as this accompany all such multiple impact sites, except that the Antarctic ellipse is the largest known on Earth. Formed by meteoroid impact dynamics, scatter ellipses result from swarms of impacting asteroids gravitationally attracted out of the asteroid belt, located 774 million kilometers (484 million miles) from Earth, or by swarms of comets or comet fragments perturbed out of the solar system’s distant Oort Cloud, 11,200 trillion kilometers (7,000 trillion miles) from Earth. Although much like the Shoemaker-Levy multiple meteoroid event of 1993 that impacted the planet Jupiter, the time of the Antarctic impact event is not yet known. And while the Antarctic scatter ellipse is not as large as that produced by the meteoroids that impacted Jupiter in 1993, it is of enormous size by Earth standards, measuring some 2000 kilometers (1200 miles) by 4000 kilometers (2400 miles). Melted rocky debris, blasted from such meteoroid craters upon impact and explosion, and known as tektites, may be carried thousands of miles from the impact site if the impact is of sufficient force. Such tektites, called australites, are found in large strewn fields in Australia some 5600 kilometers (3400 miles) from the largest proposed impact sites in the Ross Sea region. While the source of these australites has been unknown for decades, it is now believed that they have their origin in the Antarctic scatter ellipse represented by the negative gravity anomalies reported in this study.

The investigation by Drs. Weihaupt and van der Hoeven also reveals worldwide sea level implications of possible meteoroid impacts such as this on the Antarctic continental ice sheet. These results, presented at the 30th International Geographical Union conference in Glasgow, Scotland on August 18th, reveal that such a multiple meteoroid impact event on or in the vicinity of the Antarctic continental ice sheet, has the capacity to disrupt the ice sheet sufficiently to cause ice to flow to the coastline and into the adjoining ocean. An ice sheet collapse of these proportions would produce a worldwide sea level rise ranging from a few meters (few feet) to more that one hundred meters (300 feet) worldwide, depending upon the volume of continental ice carried to the ocean. Such a sea level rise would inundate lowland regions around the world, such as the Netherlands, Viet Nam, and the state of Florida in the United States. Further investigations to be undertaken by these and other investigators will attempt to determine the depth of origin of the anomalies, the age and extent of the proposed multiple meteoroid impact event, and possible global environmental and climatic changes that may be related to such a multiple meteoroid impact on Earth.

Here are the accompanying graphics.

End Release

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Last updated Sept 1, 2004