Astrologers are feeling pretty good today.   Because it's made up and not science, anything happening anywhere near a date they predict can be attribution, so talk of a 'supermoon' - a new or full moon at 90% of its closest perigee - followed by an earthquake in Japan makes them seem prescient.

Well, are they?   The supermoon which will occur March 19 will be at its closest to Earth in elliptical orbit (lunar perigee) and closer to Earth than it has been in 18 years.    How close is that?  Only about 2 degrees so unless astrologers have the kind of measurement instruments no one outside NASA has, they can't detect it.   Which means it isn't causing huge waves or earthquakes.

Astrologer Richard Nolle, who first coined the term 'supermoon' in 1979, believes that lunar perigees do cause natural disasters on Earth.   'Supermoons have a historical association with strong storms, very high tides, extreme tides and also earthquakes,' he told the Daily Mail.   But this is not possible.  Instead, he and believers only count the ones that happen during supermoons - and their timeframe is ridiculously broad.   The earthquake in Christchurch, New Zealand?  Supermoon!  Even though it was three weeks ago.   That's what confirmation bias is - the tendency to find patterns to reinforce things we already want to believe.

tsunami earthquake japan supermoon
Whirlpool due to currents from a tsunami near Oarai after an earthquake off the north-eastern coast of Japan today.   Credit: AP via Daily Mail

What astrologers don't know is that if such a thing were possible there would be hundreds of earthquakes and volcano eruptions, not one or two big ones.  And the Moon orbits us every 29.5 days so most months it reaches perigee more than once. As that orbit changes so does the distance between Earth and the moon but on March 19 it will only be about half a percent closer than it ever is every 18 years.   What gets astrologers excited is that is combined with a full moon.   What geological significance is that?  None at all, but it's pretty.   

Certainly you want to go have a look but there is no material effect from it.

Obviously if you are reading this site you are not living your life by astrology - they are contending the 2004 tsunami was related to a supermoon also, even though the tsunami occurred two weeks earlier.  So if supermoons are important they can't be responsible for something happening two weeks earlier or we would have had hundreds or more by now.

It certainly did not cause the 8.9-magnitude earthquake that hit Japan.

What is a tsunami?

Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the ocean. When tsunami waves travel inland, they get larger as the depth of the ocean decreases.   If you know your fluid dynamics you know why the speed of tsunami waves varies with ocean depth rather than the distance from the earthquake. 

How fast?   As fast as an airplane in some cases, slowing down only in shallow waters.  The largest tsunami was also in Japan,  Ishigaki Island in 1971. It was 278 feet high (that is a 30-story building) and carried a 750-ton block of coral 1.5 miles inland.

Sadly for astrologers, that was 3 years before the supermoon in 1974.

I'm not saying the world can't end, I am just saying a supermoon won't be the reason for it.   'End of the world' stories should always be in the future so rather than look stupid predicting something next week, predict something almost two years from now, like the Norse or Mayan calendar.   Those have as much geological legitimacy as a supermoon.