Dear Cecil: I'm reading this book about Australia that mentions an enormous explosion in the middle of the Australian outback, circa '94, and some dark hints that it occurred on a site occupied by those wacky Aum Shinrikyo cultists. It is further averred that they went there specifically to mine uranium in order to build an A-bomb, end of W. Civ. as we know it, yadda yadda. This didn't happen, right? This couldn't happen, right? elucidator, via the Straight Dope Message Board

Cecil replies:

Well, Western civilization didn’t end, if that’s what you’re asking, notwithstanding the impression you may get from reality TV shows. It’s unlikely the Aum Shinrikyo people went to the outback intending to mine uranium, and it’s really, really unlikely they detonated a nuclear bomb there. But — this is the weird part — the cultists did buy some property in the outback, and about the time they did, there was a massive seismic event nearby, accompanied by a fireball in the sky. Probably it was just a coincidence. But who knows? Maybe they just didn’t know that if the barbie’s knackered, don’t have a gander at the propane with a match.

The book you’re reading is undoubtedly Bill Bryson’s In a Sunburned Country. In it he reports that:

At 11:03 PM local time on May 28, 1993, a large-scale seismic disturbance, elsewhere reported as measuring 3.9 on the Richter scale, was detected near the Banjawarn sheep station in remote western Australia. The few observers in the area reported seeing a flash in the sky and hearing an explosion. The blast was 170 times more powerful than the biggest mining explosion ever recorded in the region and was consistent with a meteorite strike, but no crater could be found. In 1995, after the Aum Shinrikyo in Japan had released nerve gas in the Tokyo subway system and killed 12 people, it was revealed that the cult owned a 500,000-acre property in western Australia near the site of the mysterious boom. The cult has two former Soviet nuclear engineers in its ranks, hopes eventually to destroy the world, and maybe wanted a bit of practice, eh? In 1997, scientists finally got around to investigating this disquieting possibility. “You take my point,” Bryson writes. “This is a country … so vast and empty that a band of amateur enthusiasts could conceivably set off the world’s first nongovernmental atomic bomb on its mainland and almost four years would pass before anyone noticed.”

Nicely put, but of course we can’t leave it at that. On further investigation, it appears that the Aum Shinrikyo connection was publicized through the efforts of one Harry Mason, an Australian mining geologist and sometime UFO investigator. Having heard about the 1993 event a couple years after the fact, Mason interviewed every observer he could find within a 300-kilometer radius of Banjawarn. Several reported seeing a large fireball streak across the sky and disappear beyond the horizon, followed by a near-blinding burst of light accompanied by a loud blast, a massive seismic ground wave, and a huge red flare that shot into the sky. This in turn was followed by “a deep red-orange coloured hemisphere of opaque light” that hovered above the apparent explosion site for hours, then suddenly disappeared; another fireball an hour after the first one; and possibly a third one still later (or earlier — the observers didn’t remember). Numerous other fireballs have supposedly been spotted in western Australia in the years before and since.

Mason wrote up a report describing all this and pointing out the Aum Shinrikyo link. His report found its way into the hands of the Permanent Subcommittee on Investigations headed by U.S. senator Sam Nunn, which asked Incorporated Research Institutions for Seismology (IRIS), a university research consortium based in Washington, D.C., to look into the possibility that the cultists had somehow detonated an atom bomb. On the basis of the sketchy seismic data available, IRIS concluded that an explosion was unlikely and found that “the observations are consistent with a meteorite scenario,” notwithstanding the lack of a crater or other physical evidence.

I’ve been in touch with Harry Mason, a published version of whose report can be found at www.cheniere.org/misc/brightskies1.htm. Harry doesn’t buy the meteorite explanation, conjecturing that the fireballs were actually “concentrated slugs of infolded Tesla ray-wave E/M energy, emitting light (photons) as a by-product of interaction with air molecules to provide a hologramlike spatial form.” Harry was very kind in sharing his research with me, but still one has to say: Cheezit, man, lay off the comic books. His paper also had section headings like “Oklahoma City ‘Bombing,'” which made my lip curl before I’d read any further.

Let’s get serious. The likeliest explanation is that the boom was a meteorite strike, and the reason they haven’t found any physical evidence is that it happened in the middle of a wasteland the size of England, by Mason’s estimate. It’s like my office. You think if an asteroid fell on it, anybody could tell?

Another Opinion

(The following arrived after this column went to press.)

Dear Mr. Adams:

Thank you for your recent inquiry regarding the event observed and recorded in Western Australia on 28th May 1993. We are not aware of any further information that has come to light since the analyses undertaken between 1993 and 1997.

The event was analysed by the Incorporated Research Institute for Seismology (IRIS). They concluded that it was consistent with the impact of an iron meteorite with a radius of between 0.5 and 1.6 m. However, a search by light plane shortly after the event failed to locate any impact crater, which could be expected to be 90 m or more in diameter. They also concluded the seismogram which was recorded was inconsistent with a mine explosion, but were inconclusive as to whether it was a local earthquake.

As no impact crater has been found it is most likely that the event recorded by the seismic network was a small magnitude 3.6 earthquake, which is not unusual in this region and consistent with the seismograms. Since 1993, two earthquakes occurred in an area of 50 km around the epicentre of the 28 May 1993 event. The seismic records of these earthquakes were compared with the seismic records of the 1993 event, and showed similar characteristics consistent with typical seismic activity for Western Australia. The observation of a meteor is also not unusual in this region because of the clear skies and flat topography, but we are unaware if there was an unusually large number in the 1990s.

— Clive D.N. Collins, Urban Geoscience Division, AGSO – Geoscience Australia, Canberra, Australia

I wrote back asking what AGSO (the Australian Geological Survey Organisation) made of reports of a giant fireball concurrent with the seismic event in 1993. I got this reply:

Dear Mr. Adams:

As we do not have any information other than what was recorded on our seismic network we are unable to comment on reports of phenomena in the atmosphere. We do however note that there is no evidence of atmospheric sound waves (a ‘sonic boom’ for instance) visible on the seismic records. Evidence for these waves have been observed on records associated with known meteor sightings.

— Clive Collins

So there you go. Maybe it was a meteorite. Maybe it was an earthquake. I wouldn’t put big money on it being a concentrated slug of infolded Tesla ray-wave E/M energy, but I suppose given the scanty data available we can’t rule anything out.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.