A massive solar storm once set off ‘thousands’ of sea mines near the end of the Vietnam War

An X-class solar flare on Oct. 26, 2014, as captured by NASA’s SDO. Picture: NASA

Solar storms often come with alarming headlines about digital chaos, but mostly deliver not a lot more than a spectacular northern or southern lights show.

There are notable exceptions, such as the “Carrington Event” in 1859, which set papers in telegraph offices on fire and lit up pre-dawn skies all over the planet with incredible light shows.

A similar-sized event now, given our reliance on digital technology, has been estimated to potentially cause up to $US2.6 trillion in disruption to the US economy alone. The Earth narrowly avoided one at that scale in 2012.

Proving that damage can be done, a smaller direct hit in 1989 took out Hydro-Québec’s electricity transmission system for nine hours.

And now we’re learning of another very specific strike in 1972.

Apparently, it’s been buried in some old US Navy records, and surfaced a couple of weeks ago when researchers for a paper published in the American Geophysical Union journal Space Weather paper took a closer look at the event.

The 1972 solar storm occurred between August 2 and 4 and many of its effects were widely reported.

According to authors, a series of X-class flares – the strongest type of flare – sent the shockwave to Earth in a record time of 14.6 hours.

Among the effects, people reported:

  • Dayside radio blackouts that developed within minutes
  • High X-ray emissions for more than 16 hours, and
  • ‘Spectacular aurora’ along the southern coast of the UK bright enough to cast shadows

More alarming effects were noted after the event, including a moment where US Air Force sensors were switched on, falsely warning of a nuclear explosion somewhere on the planet.

NASA got lucky. In its version of the events on its Space Weather timeline, the flares hit in between two Apollo missions – the crew of Apollo 16 had returned to Earth in April and the crew of Apollo 17 was preparing for a moon landing in December.

If any astronauts had been in an Apollo command module, they would have absorbed “10 times the normal human dosage of radiation expected in a lifetime”.

It would likely have taken a bone marrow transplant to save their lives.

Back on Earth, the Vietnam War was in its final phase, and this is where the Space Weather researchers uncovered an alarming anecdote about the 1972 solar flares.

“There was an additional effect,” they wrote, “long buried in the Vietnam War archives that add credence to the severity of the storm impact: a nearly instantaneous, unintended detonation of dozens of sea mines south of Hai Phong, North Vietnam on 4 August 1972.”

“Ultimately the Navy concluded that the explosions had been caused by the magnetic perturbations of solar storms, the most intense in more than two decades.”

Mines in 2018 can’t be blown up by the sun. Picture: Getty Images

The mysterious explosions were reported by aircrews. And one US Navy Mineman‐Sailor, Chief Petty Officer Michael Gonzales, says it wasn’t just dozens.

In a 2015 paper “The Forgotten History; The Mining Campaigns of Vietnam 1967-1973“, Gonzalez reports:

“During the first few weeks of August, a series of extremely strong solar flares caused a fluctuation of the magnetic fields, in and around, South East Asia. The resulting chain of events caused the premature detonation of over 4,000 magnetically sensitive DSTs (Destructor mines)”.


Fortunately, the US Navy took the possibility that space weather blew up their bombs seriously, and future-proofed their weapons from then on against it happening again.

But it’s still an excellent reminder that the Sun can surprise us in under 15 hours, and with consequences we might not even know we needed to protect ourselves against.

You can read the full report here at AGU100.