Wilson da Silva

Science journalist, feature writer and editor.

Jul. 16, 1995
Published on: Sunday Age
4 min read
The main island of Moruroa Atoll, near Tahiti, which is home to French military facilities

By Wilson da Silva

RADIOACTIVITY from past French underground nuclear tests at Mururoa Atoll is already likely to be leaking into the ocean, and scientists say that further tests could lead to a sizeable collapse in its geological structure, creating tidal waves. 

An even more worrying scenario is that the long silent volcano sitting under Mururoa could be reactivated by further tests. Although most researchers consider this unlikely, they said the possibility cannot be discounted.

“It is about the worst place you could think of to conduct nuclear tests,” said Dr Richard Price, a vulcanologist at La Trobe University’s Institute of Earth and Planetary Sciences, who has extensively studied the South Pacific.

“I’d be very surprised if seepage wasn’t already happening. I’d like to see them provide some data on just how much water is actually entering their drill shafts. The French haven’t been too forthcoming with information.”

Professor Peter Davies, a geologist at the University of Sydney who took part in a scientific mission to the atoll in 1983, said that serious radioactive leakage could start within five years, if there wasn’t already some taking place.

“Considering that the slumping of the atoll margin has occurred along the south-west and north-east margin, the tests must have been perilously close to a breach,” he said. The atoll is “far from being dry and inert. It is clear that water is available for the leaching of radioactive products within days or months of an explosion”.

Some environmental groups say further French tests risk a cataclysmic breakup of the atoll and the release of radiation across the Pacific.

The claims were strengthened by vulcanologist Pierre Vincent of France’s Centre for Volcanic Research in Clermont-Ferrand, who said last week that the 180 nuclear tests already conducted at the atoll may have destabilised its structure, and that more

blasts could collapse the undersea volcano walls, creating tidal waves and spreading radioactivity.

The Mururoa volcano, which has been silent for nine million years, may be put “back into conditions of activity” by the tests, he said.

Most experts doubt the volcano could be re-activated, but said a collapse of part of the atoll was possible. “Firing these tests could cause a large landslide, and if that occurred, it would open up a whole edifice and eject a lot of radioactive material into the ocean,” Price said.

Scientists point out that even if this doesn’t occur, France has created a vast and highly toxic nuclear dump in an area of porous rocks that is surrounded by sea. Even if leakage is not yet occurring, the sea water will eventually make its way through and spread the radioactivity.

“The best case scenario almost certainly approximates leakage to the ocean within, and perhaps in less than, 500 years,” Davies said.

Once leaked, the plutonium and other heavy radioactive contaminants are ingested by local fish, who are themselves eaten by migrating fish, further concentrating the toxins on up the food chain.

Eventually, contaminated fish would end up on dinner tables around the Pacific.

Mururoa, about 1000 kilometres south-east of Tahiti, has been the site for 41 atmospheric and 139 underground blasts.

French President Jacques Chirac announced last month that at least eight more tests would be conducted at Mururoa from September before ending tests altogether. His predecessor, François Miterrand, suspended the tests in 1992.