Mystery Event In Australian Outback: Nuclear Blast, Earthquake or Meteorite?

May 28, 1997

Note to Editors: The phone number for the AGU press room is (410) 649-7419.

At the request of a U.S. Senate subcommittee on investigations, a group of scientists has been analyzing a mysterious seismic event that took place in a remote part of southwest Australia on May 28, 1993.

On that date, a group of aboriginal prospectors witnessed a radiant, star-like object traveling low across the horizon followed by a bright flash of light and a powerful explosion when the object disappeared behind a ridge. The terrorist group responsible for the March 20, 1995 poison gas attack in a Tokyo subway had attempted to enrich uranium near the epicenter of the mystery event, and Senate investigators feared the group was conducting nuclear tests in the area.

Scientists examining the event are Christal B. Hennet and Gregory E. van der Vink of Incorporated Research Institutions for Seismology in New York, Danny Harvey of the University of Colorado at Boulder, and Christopher Chyba of the University of Arizona. Harvey is a research associate at the Joint Seismic Program Center in the CU-Boulder physics department.

The researchers looked at factors such as location, depth and magnitude to distinguish between possible causes of the event, including an earthquake, a meteorite or an explosion. Their analysis ruled out a nuclear explosion and suggests an iron meteorite more than 3 meters in diameter may have been the cause of the mysterious blast.

The group, which presented its findings at this week's meeting of the American Geophysical Union in Baltimore on May 28, used seismic data collected from various stations in Australia to analyze the event.

Such a meteorite would have left a crater more than 90 meters in diameter, and the scientists are now attempting to define an area of impact so that a ground search can be undertaken.

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