Declassified report shows solar flares detonated mines

By Jonathan Griffin

A strong solar storm in 1972 caused widespread disturbances to satellites and spacecraft, and may have led to the detonation of mines during the Vietnam War, according to new research showing the event may have been a more devastating solar storm than previously thought.

A solar flare bursts off the left limb of the sun in this image captured by NASA’s Solar Dynamics Observatory Credit: NASA/SDO/Goddard/Wiessinger

In a new study in Space Weather, a journal of the American Geophysical Union, researchers pieced together data and historical records related to the solar activity of 1972 to better understand the nature of the solar storm. In the process, they uncovered an incident where sea mines off the coast of Vietnam were detonated by the solar event.

The study’s authors suggest the solar storm was a Carrington-class storm, meaning it may have been similar to the strongest storm on record, the Carrington Event of 1859. They hope the new findings will motivate further investigation of the storm and help scientists prepare for solar events in the future.

“This is a Carrington-class storm that has gone under the radar,” said Delores Knipp, a research professor at the University of Colorado Boulder and senior research associate at the High Altitude Observatory of the National Center for Atmospheric Research in Boulder, Colorado. “What I am asking scientists to do is go back and reinvestigate with new eyes.”

Intense solar activity in early August 1972 hurled hazardous radiation, solar plasma and charged particles in Earth’s direction. After reaching Earth on Aug. 4, the highly energetic particles and magnetized plasma disturbed both human technology and natural phenomena, Knipp said.

The solar activity damaged spacecraft and satellites, and led to power issues across North America. Auroras, resulting from charged particles from the Sun interacting with air in Earth’s upper atmosphere, were visible in the northern United States and southern United Kingdom.

“Had we had astronauts on the way to the Moon, it appeared that they would have become very, very ill from the radiation sickness,” Knipp said.

On the same day, while observing the coastal waters of North Vietnam from aircraft, US Navy personnel witnessed dozens of destructor sea mines exploding with no obvious cause. These mines were airdropped by the US Navy into Vietnamese waters as part of Operation Pocket Money, a mission aimed at blocking supplies from reaching North Vietnamese ports.

The Navy promptly investigated the peculiar explosions, working with the National Academy of Sciences and the National Oceanic and Atmospheric Administration, to conclude that more than 4,000 mine detonations were most likely triggered by the solar storm, Knipp said.

A now declassified report about the mining of North Vietnam from the Chief of Naval Operations at the Mine Warfare Project Office noted, “this was the first example of what happens to a major mining campaign in the face of the vagaries of nature.”

Destructor mines (DST) were developed during the Vietnam War. These were Mark 80-series GP bombs converted to mines by the addition of mine-type arming, detection and filling systems. They differ from conventional sea mines in that they can be used against land targets as well as sea targets. The Mark 36, 40 and 41 Destructors were respectively the Mark 82 [500 lbs. (227 kg)], Mark 83 [1,000 lbs. (454 kg)] and Mark 84 [2,000 lbs. (907 kg)] bombs. Arming, detection and firing were common to all three types. The following description is from “Naval Weapon Systems 1991/1992:”

Many of the destructor mines were designed to trigger if they sensed changes in magnetic fields associated with moving ships. Solar activity is known to perturb Earth’s magnetic field, and in early August 1972, the perturbations were likely strong enough to meet the magnetic requirements for detonation, Knipp said.

“I was able to connect all these things and say well, not only did the sea mines blow up and do we have pretty good evidence of that … but the likely way this would have happened was if this was really a storm of much greater proportion than anyone was understanding,” Knipp said.

As humanity becomes more intertwined with and dependent on technology, the effects of solar activity will become increasingly important, Knipp said. Dependence on satellite systems, like GPS, could make today’s world more vulnerable to another event like the 1972 storm.

“If the same storm were to occur today, how well could we withstand it?” Knipp said. “It is worth asking and answering that question.”


Paper: (open access) https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018SW002024

On the Little‐Known Consequences of the 4 August 1972 Ultra‐Fast Coronal Mass Ejecta: Facts, Commentary, and Call to Action

Abstract

Today the extreme space weather events of early August 1972 are discussed as benchmarks for Sun‐Earth transit times of solar ejecta (14.6 hr) and for solar energetic particle fluxes (10 MeV ion flux >70,000 cm−2·s−1·sr−1). Although the magnetic storm index, Dst, dipped to only −125 nT, the magnetopause was observed within 5.2 RE and the plasmapause within 2 RE. Widespread electric‐ and communication‐grid disturbances plagued North America late on 4 August. There was an additional effect, 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. The U.S. Navy attributed the dramatic event to magnetic perturbations of solar storms. Herein we discuss how such a finding is broadly consistent with terrestrial effects and technological impacts of the 4 August 1972 event and the propagation of major eruptive activity from the Sun to the Earth. We also provide insight into the solar, geophysical, and military circumstances of this extraordinary situation. In our view this storm deserves a scientific revisit as a grand challenge for the space weather community, as it provides space‐age terrestrial observations of what was likely a Carrington‐class storm.

Plain Language Summary

The extreme space weather events of early August 1972 had significant impact on the U.S. Navy, which have not been widely reported. These effects, long buried in the Vietnam War archives, add credence to the severity of the storm: a nearly instantaneous, unintended detonation of dozens of sea mines south of Hai Phong, North Vietnam on 4 August 1972. This event occurred near the end of the Vietnam War. The U.S. Navy attributed the dramatic event to magnetic perturbations of solar storms. In researching these events we determined that the widespread electric‐ and communication‐grid disturbances that plagued North America and the disturbances in southeast Asia late on 4 August likely resulted from propagation of major eruptive activity from the Sun to the Earth. The activity fits the description of a Carrington‐class storm minus the low‐latitude aurora reported in 1859. We provide insight into the solar, geophysical, and military circumstances of this extraordinary situation. In our view this storm deserves a scientific revisit as a grand challenge for the space weather community, as it provides space‐age terrestrial observations of what was likely a Carrington‐class storm.

Fig1. (a) Calcium spectroheliogram of McMath Region 11976 on 3 August 1972. (b) Hydrogen‐α solar spectroheliogram of flaring region at 0648 UT on 4 August 1972. Copyright BASS2000, Paris Observatory, PSL (used with permission). The east limb is at the left of both images. (c) Hourly‐average solar wind plasma data 4–11 August 1972 (Zastenker et al., 1978). (d) Magnetosheath magnetic measurements for 2120 – 2230 UT from ATS 5 geosynchronous spacecraft at 15 LT (Cahill & Skillman, 1977); (e) Manila Observatory magnetic X component variations 4 August 17 UT to 5 August 7 UT (Salcedo, 1973). The vertical jump at 2240 UT represents a 168‐nT/min increase. After the second sudden commencement giant geomagnetic pulsations were present in the magnetosphere.

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42 thoughts on “Declassified report shows solar flares detonated mines

  1. Interesting.
    Although, if a Carrington event can go almost unnoticed for 40 years, perhaps they are not as impactful as once thought?

    • The original Carrington event induced huge voltages on telegraph lines.

      Telegraph systems all over Europe and North America failed, in some cases giving telegraph operators electric shocks.[17] Telegraph pylons threw sparks.[18] Some telegraph operators could continue to send and receive messages despite having disconnected their power supplies. link

      The telegraph lines were the only long lengths of wire at the time, there were no power lines.

      Any modern line will have some kind of overvoltage protection. That would limit physical damage. That said, there would still be power and communications outages. My guess is that things like ground based aids to air navigation (VOR, TACAN, ILS, etc.) would be unaffected. I don’t know about GPS. It could be degraded by the loss of some satellites.

      • Since GPS is a military system with auxiliary civilian use, I am near certain GPS satellites are rad hardened. There are various tricks for doing so including exotic expensive semiconductors and additional isolation circuitry. Maxwell Technologies in San Diego has two businesses: supercapacitors, originally developed for the Navy (think rail guns), and rad hardened CPU’s for military satellites.

        • When I started in the industry in the 1970s, it seemed to me that mil spec was a bigger deal than it is now. It seemed to be that you couldn’t look in a catalog without being offered mil spec or civilian for almost any component. eg. 5400 vs. 7400 Has mil spec faded a bit or is it just a relatively smaller part of a much bigger industry?

          • They’re still around, but the proliferation of standards organizations (ASME, ASTM, IEEE, ISO, etc) and the concomitant factorially huge torrent of standards pouring out of them, and MIL-SPEC [-STD, -HDBK, etc] have lost their preeminent status. For a while, in fact, the US military was getting away from their use. MIL-HDBK 5, a treasure trove of material properties, was no longer maintained the last I heard. My wife recently worked on the new ICBM program, GBSD, and I asked her if MIL-SPECs were still out of fashion. She said that the Air Force, at least, has returned to their use. She had personally found that a lot of the commercial “standards” were mere guidelines, unlike the MIL- documents.

        • The disruption of GPS service is not necessarily an SV hardware failure under a severe geomagnetic storm, but a severe disturbance to ionospheric structure and density which the modelling of GPS signal propagation time accuracy depends on.

    • Good question.
      My take away is these events manifest on a spectrum. The 19th century Carrington event lit up the lower atmosphere according to the record.
      The 1970s event appears to have been much less energetic.
      So the 19th century event would have been much more powerful, possibly an order of magnitude, than the event in the 1970s.
      We forget how rough physics can play at our peril.

      • Here is something to think about. Earth’s magnetic field is about 10% weaker now than during the Carrington event (Decreasing at 50% every 1400 years) Wouldn’t that mean that the effects would be worse on technology than happened during the Carrington event?

  2. If a solar event strong enough to set off mines under the ocean can go unnoticed, what other solar impacts upon the Earth’s ecosystem are happening that are also too subtle to have been noticed? And how do they affect climate?

    Climate scientists can’t answer that as they haven’t considered it even worth study.

  3. Interesting report, Mr. Griffin. I know geophysicists used to (still do?) track sun storms for the magnetic flux affecting underway magnetic surveys. When I was in Vietnam, 1969, we regularly saw passing thunderstorms set off perimeter mines and fugas containers. These devices had wires running to them with a connection to a command box, with circuit breakers pulled, of course. However the lightning strike near the wire evidentally sent enough current along to the mine to detonate. Our heliport air traffic control tower, Sabre, where I worked, was directly on the perimeter and I can assure you these detonations caused a lot of reaction.

  4. I think the question that needs to be asked is what level of magnetic disturbance would be sufficient to set off the mines, and what impact would that level of disturbance have on instruments, products, processes our current society uses?

    • These mines were designed to go off from the influence of a steel hulled ship passing nearby. So a difference smaller than the magnitude of Earth’s magnetic field, over a period of maybe a second or longer. The mention of use on land suggests a passing steel armored tank would also trigger them.

  5. Sorry, but I was in the USN in 1972.
    After leaving Vietnam in 71, as an Electronics Warfare Officer I read daily high level security reports and never read anything about this. A mine under water without connecting wires is highly unlikely to go off without the appropriate causes (acoustical or magnetic). A solar/magnetic flare would not cause this.
    Someone is looking for publicity.

    • Solar flares push the Earth’s magnetic field around. This will definitely result in magnetic field changes that a mine could detect.

    • @MarkW

      Solar flares push the Earth’s magnetic field around. This will definitely result in magnetic field changes that a mine could detect.

      But this was not a solar flare. It was classified as ‘ultrafast coronal mass ejection (CME). The largest solar flare in recent times occurred on 4 Nov 2003 and was initially classified as intensity X28. Some suggest it may have been stronger, up to X45.
      https://en.wikipedia.org/wiki/Solar_flare

      The 1859 Carrington flare has been estimated to be of comparable intensity (X15 to X45) https://core.ac.uk/download/pdf/9697855.pdf

      I seem to recall that Leif Svalgaard claimed that X85 is the maximum possible upper bound on solar flare intensities. 😐

      • An X85 flare would completely strip away the ozone protection for the Sun facing part of the Earth’s stratosphere. Even with mixing, it would takes months to years for the stratosphere’s ozone levels to recover back to protective levels. Much biologic sterilization to the surface would occur, both immediately with such an event and in the months that followed for the entire Earth. Some people could retreat to underground and protective structures to survive the resulting UV flux to ground level, but mass world-wide starvation would surely ensue due to crop destruction from intense solar UV reaching ground level for months. Stored seed reserves, protected from UV radiation, would be necessary to resume population sustaining replanting once UV levels abated to safe levels for planting. But billions would still die in the time before harvests brought food availablity to support the survivors. And animal populations would be devastated as well due to vegetation die offs from UV destruction. An X85 would be a true ELE.

        • Sun’s UV creates 12% of the ozone layer everyday through the ozone-oxygen cycle. UV-C can damage plant’s DNA and cause mutations. But that’s not the same as total crop destruction. People can protect themselves from UV by staying indoors and sunscreen lotion.

  6. I was 16yo in the summer of 1972 living in Northern Michigan, USA and remember a spat of spectacular northern lights. They completely covered the sky and went horizon to horizon. The sky looked like it was literally crawling with greens, purples and white swirling waves. The light was bright enough to easily fish well after dark. So amazing it was almost scary. It was like no other northern lights we had experienced.
    At the time we wondered if it could have been caused by the Soviets.

    Must have been this event.

  7. There should be some evidence of aircraft malfunctions in Vietnam if there was a Carrington sized event. In 1972 there were fixed wing aircraft in the air every day. There were even more helicopters airborne every day.

    Maintenance records for unexplained breaker malfunctions in the aircraft or other electronic glitches should show up if the records are available for 8/4/1972 and shortly after.

    • During the original Carrington event, voltage built up on telegraph lines that were large enough to make them spark.
      So, if a line 100s of miles long can build up a charge in the 100 to 200 volt range. How much voltage can build up on a line a few dozen of feet long, inside a metal tube.

    • There were satellite failures and grid electrical disturbances associated with this event, likely due to degradation of solar panels from the proton/electron flux impacts. This is discussed by the authors in the paper referenced above.

  8. This is important for general readers to see if there was a Carrington class event in modern times and most people never knew it even occurred. They need perspective in order to move on, much like the very last minute perspective they got on the end of the Mayan calendar.

    • “So, is this what caused the “Snowball Earth” scare in the 70’s?”

      No, it was the cold temperatures at the time that caused scientists to think the Earth was heading towards another ice age. The Earth’s temperature cooled off from the 1940’s to the 1970’s, then it started warming up in the late 1970’s and climate scientists switched from scaremongering about ice ages to scaremongering about an overheating Earth.

      Climate scientists seem to think that once a trend is established, it will go on forever. It doesn’t. Things change.

  9. When British Columbia spent $1billion to put “smart meters” in 600,000 households in 2011, I asked our utility how vulnerable they might be to a Carrington event.
    The line went dead.

    • The real damage to the grid from a Carrington events will be on the HV tranmission lines and connecting substations. The energy spikes likely will not propagate to the local customer level due to the extensive systems of breakers and line interrupters. So the customer, end consumer meters will not the problem.

      The unimaginable problem would be the damage to very expensive, and in some cases one-of-a-kind line equipment like specialty High voltage (HV) transformers and 3 phase HV circuit interruptors, that could takes months to replace and repair damaged HV transmision lines. There are unique, one-a-kind transformers on some systems that were custom built for that installation that could take a year of more to manufacture and install to replace a damaged unit.

      • “The unimaginable problem would be the damage to very expensive, and in some cases one-of-a-kind line equipment like specialty High voltage (HV) transformers and 3 phase HV circuit interruptors, that could takes months to replace and repair damaged HV transmision lines. There are unique, one-a-kind transformers on some systems that were custom built for that installation that could take a year of more to manufacture and install to replace a damaged unit.”

        I heard the head of a commission studying this subject a few months ago say that these essential parts of the electric grid could be protected from power surges by our spending about $4 billion on new equipment. That seems like a small price to pay to secure the electrical grid.

        As you say, if some of this unique equipment gets destroyed, it could take years to get things back up and running. We can’t afford to be without power for even a few days, much less years. Fixing this problem should be a top priority of our government.

  10. There were indeed reported power fluctuations in North America with this event. The authors of this paper discussed it in fact:

    From the paper referenced above:

    “The IP disturbances created geomagnetically induced current effects in North American power and communications lines. Albertson and Thorson (1974) listed numerous United States and Canadian power companies that reported minor to strong power issues on 4–5 August 1972. They show strong induced current disturbances as far south as the US states of Maryland and Ohio. According to Odenwald (2015) significant voltage swings and power disruptions were reported in northern tier U.S. states. In Newfoundland, Canada, geomagnetically induced currents activated protective relays many times on 4–5 August. The Manitoba Hydro Company recorded 120 MW drops in power supplied to Minnesota in only a few minutes. Anderson et al. (1974) reported an outage on the L4 American Telephone and Telegraph cable connecting the U.S. states of Illinois and Iowa. The induced electric field of 7.0 V/km, which exceeded shutdown threshold for high current, accompanied magnetic field variations (dB/dt) of ~ 800 nT/min at 2240–2242 UT (the time of the L4 outage). In central and western Canada, Boteler and Jansen van Beek (1999) estimated that dB/dt exceeded ~2,000 nT/min coincident with the SI. “

    Furthermore, section 1.4 Naval Effects has a relatively extensive discussion on the detonating magnetic mines n this paper and are worth reading for those curious.

    Here’s the historical record for Planetary A index (as Ap was called then) for July-August 1972.
    https://i.postimg.cc/t4bsvJK4/Screen-Shot-2018-11-15-at-10-33-27-AM.png
    (note: relatively accurate historical Ap data goes back to 1936, with the full record to 1932)

    This 1972 event originated from McMath Active Region 11976, a solar northern hemisphere beta gamma delta region of likely classification “DKC” during the declining phase of SC 20. SC 20 lasted 11.4 years, beginning in October 1964 and ending in March 1976.
    (for info on the sunspot classifications, go to SIDC web page here:
    http://sidc.oma.be/educational/classification.php )

    The early August 1972 CME’s were certainly the strongest solar event to strike Earth during SC 20. As they point out in the paper, the magnitude of the x-ray event was estimated during that era (1974):

    “At the other end of the solar spectrum, the SOLRAD‐9 satellite X‐ray detector saturated at what would be an X5.1 magnitude in the current National Oceanographic and Atmospheric Administration (NOAA) solar X‐ray classification (but clearly exceeded that level, see Dere et al., 1973, p 309). Ohshio (1974), using ionospheric radio wave phase propagation disturbances, estimated the flare class as ~X20.

    So a (roughly) X20 event for the 4 August 1972 flare is still 2 order of magnitude below an X40 class Carrington event. For reference, the strongest solar event to strike Earth from the current SC 24 was an X9.3 event with an associated strong CME that erupted from AR 12673 at 1202 UTC on 6 September 2017. Of note, the 1 September 1859 Carrington event (with geomagnetic and intense auroral events in the following days) occurred approx 6 months before to SC 10 peak in February 1860.
    A modern view of AR 12673 taken on August 5, 2017 using SDO’s HMI and UV imaging capabilities is here:
    http://www.solen.info/solar/old_reports/2017/september/images/AR_12673_20170905_2345.png

    All of these strong x-ray class flares and associated CMEs initiate from connected twisted magnetic fields of what are classified as beta gamma delta (BGD) active region sunspots mentioned above. How the delta character of intermixed magnetic polarity is the subject of much on-going research and modeling using magneto-hydrodynamic (MHD) computer simulations.

    The deeper question is, “Why do these magnetic delta characteristic regions form at all within beta gamma ARs?”
    What initiates the likely flux tube density anomalies (suggested from computer MHD simulations) much deeper in the solar convective zone, that once these flux tube density anomalies reach the solar surface (the photosphere), their twisted, nasty behavior is already in progress?

    On the deeper questions of what process perturbs the orderly rising of magnetic flux tubes from deep in the CZ as the proceed to the solar surface, I have a revolutionary idea and some observational evidence to support it that I’m working on and hope to publish in the next few months. If studies down the road support my idea, then these intense flares/CMEs from BGD AR’s can be anticipated some 13-18 days out from their eruptions. Additionally, my idea if supported by future observations would explain the mysterious reason for simultaneous flaring and how sympathetic flaring may start.

    (For what is simultaneous/sympathetic flaring, Read here: http://www.stce.be/news/249/welcome.html )

    • Joel — a small nit. You said “So a (roughly) X20 event for the 4 August 1972 flare is still 2 order of magnitude below an X40 class Carrington event. For reference, the strongest solar event to strike Earth from the current SC 24 was an X9.3 event with an associated strong CME that erupted from AR 12673 at 1202 UTC on 6 September 2017.”

      An X20 event is 2.0 mW/m2 in soft Xray flux, while an X40 event is 4.0 mW/m2, just a factor of two, not two orders of magnitude difference. The letter X flares are 10X the letter M flares in scale, but the number following the letter is a multiplier, so an X8 event is four times a much power as an X2 event.

      The Wikipedia article on Solar Flares is somewhat unclear on exactly how the numbering for M1-M9 and X1-X9 events are to be interpreted and how the X10-Xnn values are related to them. But the 2004 Space Sciences article “Ionosphere gives size of greatest solar flare” by Thompson, Rodgers and Dowden at https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2003GL019345 makes it clear. It also estimates the 2 Nov 2003 event at X45.

  11. Leif can you let us know? Since the sun **seems** to be heading into a somewhat quiet phase for the next few decades, does that reduce the chance of a CME and thus a Carrington event?

      • That’s not good news. The government should be spending money on hardening the grid, which if it fails will definitely cause millions (if not hundreds of millions of deaths) within months. Starvation first, because without electricy you can’t pump fuel, and if you can’t pump fuel, you can’t deliever food to the stores, then shortly thereafter you will have people dying of cholera and dysentery because the sewer plants can’t operate, that is ot to mention all the people in large cities who will die of thirst because there isn’t power to pump the water to the city.

    • Mines and bombs in storage aren’t armed. Magnetic mines are most definitely not armed until after deployment.

    • Because those mines were designed to blow up when they detected a change in the local geomagnetic field strong enough to indicate a ship. Unfortunately, they didn’t account for natural fluctuations.

  12. For years I have occasionally had my memory jogged to recall seeing the strange glowing sky as I stood beside a small lake in Bucuresti, Romania.
    I had the memories recalled as I watched the Aurora Borealis displays near Nordkapp, Far northern Norway.
    At the time in Bucuresti, I remember doubting that the greenish glows were due to solar discharges as I was hundreds of miles/kilometres too far south for the equivalent of the ‘Northern Lights of old Aberdeen’ ( the local Aberdeen name for the Aurora Borealis sometimes seen around Aberdeen, Angus, Scotland, UK.
    Now I am happy to know that my suspicions of the cause were right.

  13. FYI, the WW2 German mine was set to detonate at 50 milli-Gauss.

    A Carrington effect that rang the Garth’s magnetic field in that range would detonate the mine.

    See at around 41 minutes at the video link posted above.

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