Kiwi tsunami bomb back in the news

20:53, Jan 02 2013

One of New Zealand's best kept World War ll secrets, a tsunami bomb to attack Japan, is making headlines again 14 years after its cover was last blown.

London news sites the Daily Mail and the Daily Telegraph, in a stories appearing around the world this week, say the United States and New Zealand conducted secret tests during 1944 of a "tsunami bomb" designed to destroy cities by using underwater explosions to trigger the waves.

As was revealed in 1999, when the government declassified the "Project Seal" paperwork, much of the testing was done at Army Bay on Auckland's Whangaparaoa Peninsula.

One of the survivors of the covert group, Toby Laing of Nelson, said in 1999 that he was left with a lasting legacy.

"It was 'bang, bang, bang' all day long, that's why I'm so deaf now," Laing, then 87, said at the time.

Nearly 4000 bombs were exploded at Whangaparaoa and in New Caledonia in a bid to generate a tsunami.

Seal proponents called it an "awesome" weapon of "tremendous importance chosen to administer the coup de grace to Japan".

US Navy South Pacific commander Admiral Bull Halsey wrote to the New Zealand Government, asking them to work on it.

"Inundation in amphibious warfare has definite and far-reaching possibilities as an offensive weapon," he wrote.

A New Zealand author, Ray Waru, told the Telegraph he discovered the files buried at the national archives.

"It was absolutely astonishing," said Waru.

"First that anyone would come up with the idea of developing a weapon of mass destruction based on a tsunami ... and also that New Zealand seems to have successfully developed it to the degree that it might have worked."

It didn't come close.

An Auckland University engineering professor in charge of the project, Lieutenant Colonel Thomas Leech, predicted 11-metre high waves up to four kilometres from an explosion with 2000 tons of high explosive.

"I can definitely state that I could inundate the Hutt Valley, Wellington City, and the suburbs adjacent to Lyall Bay," Leech said at the time.

But Laing said in 1999 the experiments at the dam were a failure, with few explosions producing more than a ripple.

"If you were in a small boat, you could have ridden out some of the waves," he said.

The files never revealed the intended target, but Laing said they all guessed it was intended for Japan.

At Whangaparaoa, Seal had a fenced-off compound holding a large dam in a gully.

While everyone else watched from safe positions, Laing would walk along a platform built out into the dam, set off the explosive - and run.

Seal was probably the biggest war research project New Zealand undertook, with 31 scientists and technicians from Department of Scientific and Industrial Research (DSIR), who were made honorary officers of the NZ Army Engineers.

They were ordered to bring their own slide rules and graph paper.

But the head of the DSIR, Dr (later Sir) Ernest Marsden, was appalled at it and had it closed down in January 1945.

It never came close to generating a tsunami but with the Cold War, it was reactivated in 1948, and run using engineering students.

Leech, who died in his native Australia in 1973, missed out on the trip but a member of the US board of assessors of atomic tests, Dr Karl Compton, was sent to New Zealand instead.

"Dr Compton is impressed with Professor Leech's deductions on the Seal project and is prepared to recommend to the Joint Chiefs of Staff that all technical data from the test relevant to the Seal project should be made available to the New Zealand Government for further study by Professor Leech," said a July 1946 letter from Washington to Wellington.

was made a Commander of the British Empire in 1947 with the New Zealand Press Association reporting that he had been closely associated with a secret weapon which was "an effective alternative to the atomic bomb".

At the time The Dominion reported that his work "cannot even be hinted at because of security and other matters".

Leech returned to his native Australia in 1950 where he later was appointed to a project to investigate the vulnerability of Snowy Mountain dams to nuclear attack. He died in 1973.

Seal was reputedly well known in Auckland academic circles and many in the Engineer School knew the theory and knew it would not work.

But because it was secret they were not allowed to let on that they knew, and thus it continued to have a quiet half-life.

Another secret that has since come out is that New Zealand sent 11 physicists to a super-secret project in the US.

That was the Manhattan Project out of which came the Hiroshima and Nagasaki atomic bombs which ended World War Two.