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Debunking the "Supermoon" Theory of Japan's Earthquake and Tsunami

Did the upcoming "supermoon" cause the massive 8.9-magnitude earthquake near Japan and subsequent deadly tsunami? No, it didn't; here's why.

This morning’s massive 8.9-magnitude earthquake and deadly tsunami in Japan resulted in a slew of headlines about the environmental havoc-wreaking power of the upcoming "supermoon." But in fact, given the moon's current position, its effects on earthly tides should be at their least. Here's where the reports went wrong. 

Where did the term supermoon originate?

According to AccuWeather blogger Mark Paquette, the term "supermoon" originated on the website of astrologer Richard Nolle. Paquette said in early March that a new or full moon at 90% or more of its closest perigee (the point in the orbit nearest to the center of the earth) qualifies as a supermoon. That makes the March 19 full moon a supermoon, because the crest of the moon’s full phase comes within an hour of the moon’s closest point to Earth.

Here’s what’s true—and false—about the moon on March 19.

False: The Japanese earthquake on March 11 is an example of a supermoon causing earthly effects. Not only is this untrue, the March 11 moon shows exactly the opposite, since the moon is not particularly close to Earth on March 11, nor is it full or new moon (aligned with the sun and Earth). In fact, the moon on March 11 is close to first quarter—at a right angle to the Earth/sun line. Thus—according to the supermoon-earthquake connection theory—the moon’s effect on earthly water and solid rock tides should be at its least today.

False: The last times the full moon was at perigee were 1955, 1974, 1992 and 2005. Not so. Full moon and perigee closely realign more often than that – in periods of a little more than 413 days (about 1 year 1 month and 18 days). There are, of course, differences in how closely the full moon aligns with the moon’s closest point to Earth for the month. On March 19, 2011, there is about an hour difference between the full moon and perigee. On July 21, 2005, the difference was about 9 hours.

False: A supermoon caused the December 26, 2004 tsunami in Indonesia. It did not. We all remember the devastating earthquake in the Indian Ocean that day. It created a tsunami that plowed into coastlines and caused the deaths of more than 200,000 people. The December 2004 tsunami was especially deadly along the coast of Indonesia. In terms of loss of life, it was the worst tsunami in recorded history. There was a full moon that day, but it was not a supermoon. In fact, the moon on the day of the 2004 Indonesian tsunami was nearly its farthest from Earth. The moon was closest two weeks later on January 10, 2005.

True: Some astrologers and even astronomers are using the term "supermoon" to describe the March 19, 2011 full moon. What makes it super is that—on the day of the March 2011 full moon—the moon will also be closest to Earth for the month. The March 19 full moon will be 221,567 miles from Earth, in contrast to the moon’s average distance of about 239,000 miles. No full moon will be this close to Earth again until November 14, 2016.

The moon is full every month, and there is a connection between full moon and earthly tides. At full moon, the sun, Earth, and moon lie more or less along a line in space. At these times, the gravity of the sun and moon are reinforcing each other. That’s why, every month around the time of full moon, people along the coast experience maximum high (and low) tides known as spring tides. Actually, there are two spring tides each month, one at full moon and the other at new moon, as shown in the illustration below.

What does this mean for the March 11 moon? Not a thing. On March 11, 2011, the moon is not particularly close to Earth, nor is it aligned with the Earth and sun.

As the moon orbits Earth, its gravity works with or against that of the sun to create the month's highest and lowest tides, called spring and neap tides. Because water has a momentum of its own, the actual spring and neap tides lag a day or so behind the moon phases. (Wikimedia Commons)

A word about the tides

Halfway between each new and full moon – at the first and last quarter moon phase – the sun and moon are at right angles as seen from Earth. Then the sun’s gravity is working against the gravity of the moon, as the moon pulls on the sea. This is the neap tide: the tide’s range is at its minimum.

There is about a seven-day interval between spring tides and neap tides.

Supermoons and disasters

The March 19, 2011 full moon is a close one. That’s absolutely true. A close full or new moon does connect— regularly, frequently, cyclically—with greatest tidal maximums and minimums known as spring tides. That is also true.

However, the March 11, 2011 earthquake and tsunami in Japan occurred when the moon was near first quarter, and not particularly close to Earth. March 11, 2011 should be a time of neap tides—or least tidal range—not at a time of high spring tides. The March 11 moon is not an example of a supermoon.

The takeaway

I first heard about a possible connection between a supermoon and earthly disasters from a website called Psychic Connection. It predicted "severe weather patterns, increased seismic activity, tsunamis and more volcanic eruptions than normal."

In my 40 years of writing about the sky, I’ve never heard of a connection between full moons and severe weather. Can’t comment on that one.

There are mentions in the scientific literature of a possible connection between full moons and geologic activity. The moon does indeed cause tides in the solid body of Earth, just as it causes ocean tides. So it’s logical to assume an especially close full moon might cause geologic activity to increase, and occasionally I’ve seen random (dare I say "fringe?") studies suggesting this connection. In reality, is the connection between the moon and geologic activity a strong one? I’ve never seen a study showing a striking pattern between close full moons and increased geologic activity.

Will the March 19, 2011 full moon—which coincides with the moon’s closest point to Earth—bring more earthquakes and tsunamis? Will it cause volcanic eruptions? Let me ask another question first. Why, I wonder, do people want to believe in unfounded predictions for disasters?

The moon’s distance from Earth is changing continually. The full moon on March 19 will be a close one, but there’s no scientific evidence it will cause any of those events. The March 11 moon does not prove the supermoon-earthquake theory. In fact, it disproves it. Plus we know of closer full moons than the March 19 moon that did no harm.

Will the March 19, 2011 close full moon cause floods? Yes, that’s different. Now we’re on more solid ground. Close full moons do cause maximum tidal ranges. So if a storm moves into a coastline on the day a full moon is closest, it can cause flooding along that coast. If you live along a coast, and a storm is heading your way on or around March 19...expect possible flooding and take precautions.

I don’t believe science knows everything. Clearly, it doesn’t. But we live in a complicated world, a world that features gobs of misinformation flying willy-nilly on the Interwebs, terrifying people at every turn. So – I believe – it’s important to separate fact from fiction. The March 19, 2011 supermoon is interesting, but it’s no reason to think that more earthly disasters are looming on the near horizon. Better to focus instead on what’s really important now—looking to the reality of the March 11, 2011 8.9-magnitude earthquake in Japan and subsequent tsunami in the Pacific—and responding with our hopes, prayers and support.

Understanding moon phases

Written by Deborah

Deborah Byrd is Founder and President of EarthSky, which she created in 1991. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. She’s Editor-in-Chief of all EarthSky websites, including and EarthSky en Español. She serves on EarthSky’s Editorial Board and leads EarthSky’s community on Facebook. She oversees and helps host EarthSky’s science podcast series – now in 90-second, 60-second, 8-minute, 22-minute audio formats, and in video – in English and Spanish with 20 or so new EarthSky science podcasts released every Monday to 1,200+ broadcast outlets, and heard on a variety of online platforms each week including iTunes and Odeo. A science communicator and educator for 30+ years, Byrd believes in science as a force for good in the world and as a vital tool for the 21st century. Astrophysics, the night sky and imagining space travel are among her most enduring lifelong passions.

Read more coverage of the Japan earthquake.

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  • Hholmes

    So my question is this if the tide is at its lowest during a Super Moon, it would seem that way over the otherside opposite the full moon locale the otherside of the ocean could not it have a tsunami? Lowtide somewhere means high tide elsewhere, yes? Of course Im thinking logically and have no expertise in this area, just curious.

  • Angel

    I wish people who study astronomy take the time to study
    astrology as well. You can't really argue anything unless you know both sides
    in and out. All this proves was an earthquake wasn't the result of a
    "super" moon. But a natural disaster did peak on the full moon at
    least twice in this article and killed many people. Astronomy as I recalled in
    college, teaches one to make up theories that "seem" logical.
    Oh...that is SOOOOO much better than While astrology
    cannot predict the exact events yet, it can give you a general idea. And
    generally natural disaster around the full moon, due to tidal wave fluctuation
    is totally possible. Though it may not happen every full moon. There is always
    more to it than a small space on the internet can explain. But great attempt to
    make a "logical" argument.

  • Timothy Wenzel

    Science has proven to a point that without our moon, life could not have evolved on Earth. Why? This is due to the tidal motions of the Earth's oceans. Einstein proved that mass and distance are the two strongest factors in the effect of gravity. The plates of the earth, by measure, have a higher density than that of the surrounding water. The effect of a neap tide would decrease the factor of pressure on the surface of the Earth's crust. These releases of pressure in relatively thin areas of the crust near geologically active areas near Hawai'i have shown that tide does have an effect on volcanic activity. We must, therefore, not completely discount the moon's effect on the tectonic activity of the Earth. Just as the article pointed out that tides do not exactly follow the phase of the moon, but lag to some degree, the moons overall effect on the Earth's crust must follow the same sequence. I don't buy into prediction of events by the current state of heavenly bodies, but there is an effect. How we utilize collected data and measure them is another factor altogether.

  • Chenki R

    Moon doesn’t strike bullets at Earth, but it sets Time-bombs whenever come nearer to Earth. I’m sure it will initiate another mover by setting another Time-bomb. Remember we are revolving fast but we are floating with slower moves. Only the moment will reveal. Actually we are born from a move not at the birth. Birth is only a revelation.

  • christopher weiss

    Is no one willing to speak the truth? We all know it was Chuck Norris! He was angry that no one said, "Happy Birthday!" to him the day before.

  • John Plummer

    Silly people. It was caused by global warming and by pumping vast amounts of oil out of the Middle East which caused presure to build up on opposite side of the world.

  • Daniel Smith

    There was a movie on Syfy channel last night about an impact on the moon causing natural disasters. Could be related. Some people will believe anything.

  • Chris Reich

    First, I am an amateur astronomer with many years of experience and in-depth study---formal and informal. But, feel free to dismiss anything I say based on your preset personal bias.

    Let's start with reason. The movement of tectonic plates is very difficult to predict. To date, we have only crude means of guessing when shift might occur such as measuring deep heat and interpreting that as pressure building which might trigger a shift. There are other data gathered in an attempt to discover enough correlation to make a prediction. We have no such means as yet. We are dealing with a very big system that has a tipping point we cannot predict.

    Try this experiment. Watch an hour glass as the sand falls. Periodically, the little mountain will collapse. No one can predict the exact moment that will happen. As you enlarge the scale, you also dilate the time. So, even though we can say, for example, that every 3-4 seconds our little mountain will collapse, it could very well go for 5 seconds without collapse. It could fall twice in 2 seconds. In a huge system, that time becomes years or decades or centuries.

    There is a "tipping point" that triggers the event. Does the moon have an effect? Probably. Enough to trigger an event? I don't think that can be said with certainty because it might depend on how close the system is to the tipping point.
    Now, consider the force of gravity. Gravity is a very weak force. In fact, it's termed "the weak force" by science. Weak? Seems pretty strong to me if the moon can pull the entire ocean around! But it's not strong. Lift a pen from your desk. In doing that, you are defeating the entire gravitational pull of the earth. Jump up. Again, you are able to defeat earth's hold on you albeit only for a moment. (When you stop putting energy in, gravity wins)

    Not to get too technical but it's good to have some understanding about gravity. The force is governed by what is called the inverse square law. That means the pull of gravity diminishes by an amount equal to the square of the change in distance. We are sitting about 4,000 miles from the center of the earth's mass---for simplicity sake. (Please, I don't need to be peer reviewed here) So if you go 8,000 miles 'up' (twice the distance from the center of mass) the gravitation pull is 1/4th as strong. (2X as far means 2 squared is 4). The moon, is on average 250,000 miles away. Even at this 'closest' point, about 221,000 miles, the difference in force is not much.
    Finally, let's consider the real whacky stuff like destruction being wrought from alignment with the center of the galaxy. Now you're talking about 60-70 MILLION light years away. Do the math.

    Wrap it up Chris. Okay, here's the point. We do not have the scientific means to predict catastrophe. There is , with tectonic plate shift, a 'tipping point' but that is very difficult to nail down. Sure, a full moon could be the straw that breaks the camel's back. There has to be that proverbial straw. But this moon is only that, a straw. It's not a sack of sand.

    Chris Reich

  • Georg S

    Please, everyone read and absorb Deborah Byrd's superb EarthSky article. It's near-perfect in its level-headed good science, and balance' exactly the quality of reporting that ALL Media should foster and promulgate. The Media are typically too ready to spotlight or feature mystical and uninformed speculations, especially if there's an "us-versus-them" anti-authority color. Read what you choose, but read carefully. We hear everything, but do we listen? Let's hope the Media are listening.

  • Ken McCabe

    Wow... any intelligent comments here??? Zack, she did not state that the 2004 Indonesian earthquake/tsunami was the worst earthquake AND tsunami in terms of life lost in recent history, she said it was the deadliest TSUNAMI (you added earthquake). Haiti was a deadlier earthquake, but had no tsunami. The tsunami that resulted from the Indonesian earthquake WAS INDEED the deadliest tsunami ever recorded (and it was not caused by the moon).

    The difference between the astronomers and the astrologers is that astronomers look for REAL patterns in the sky, not imiganiary ones!

  • jayaveeriah

    The new moon and full moon are having control on earth quakes and tsunamis . Definitely the increase of tides during the full moon and new moon making thrusts on the tectonic plates and shaking them resulting tremors, earth quakes and tsunamis .

    Due to global warming , there is an increase in sea level as well the sea water quantum also been increased , thereby earth dynamics might have deviated due to quantum increase of water body to an extend, causing all these troubles. May be the nature is executing some correction steps to balance it self . We may expect some after effects during super moon too.


    An astronomer I know told me that the difference between the astronomers and the astrologers can be summed up by saying that the "scientific" astronomers don't think patterns in the sky are significant. He used the term "coincidental." Well, just because we don't understand it, it doesn't mean the pattern's not significant.

    A blog I read the other day said this... (March 4, 2011 post) "Moreover, with Uranus crossing over into tropical Aries on March 11-12, just before the Full perigee Moon of March 19, we can expect strong celestial inclinations that can spark powerful earthquakes and the eruption of volcanoes." Not Nolle, btw. Sagan, I hope you're paying attention.

  • barb lern

    so i'd like to hear from anyone about the increase in earthquakes and volcano eruptions. do we know enough about how the universe affects our planet. as our planet comes into alignment with the center of the milky way is this what is affecting us here. are these just little episodes leading to something bigger.

  • Bennett White

    Please, if you are going to do an article on earthquakes and the planets, lets see some in depth research and not this National Enquirer crap, shame on you Fast Company your way better than that!!

  • Zack Wilson

    I'm not a scientist, but it is obvious that this writer has NOT done her homework with the few statistics that I do know, and as a lay person on the matter that creates a huge red flag to the general quality of this article.

    She states that the 2004 Indonesian earthquake/tsunami was the worst earthquake and tsunami in terms of life lost in recent history. That's not even close. There are five earthquakes that have had more loss of life than the Indonesian tragedy ( ). Including one just a year ago, Haiti, which had about 80,000 more casualties.

    She seems knowledgeable on the rest of the material, but doesn't really sight any credible sources. I'm surprised that a well-known publication would let something run like this without fact checking, as it seems ironic with the subject nature of the article.

  • B. G.

    you should read that part of the article again.
    "We all remember the devastating earthquake in the Indian Ocean that day. It created a tsunami that plowed into coastlines and caused the deaths of more than 200,000 people. The December 2004 tsunami was especially deadly along the coast of Indonesia. In terms of loss of life, it was the worst tsunami in recorded history."
    she's talking about the tsunami not the earthquake. the underwater earthquake created the tsunami.
    and you should never quote wiki as a valid reference since the content is not "peer reviewed". we can all edit articles in wikipedia. you simply need an account.

  • joe penn

    Zack, I think you need to look again, she/he did not say:

    "She states that the 2004 Indonesian earthquake/tsunami was the worst earthquake and tsunami in terms of life lost in recent history"

    She/He Said:

    "The December 2004 tsunami was especially deadly along the coast of Indonesia. In terms of loss of life, it was the worst tsunami in recorded history"

    And that is 100% correct.