The popular myth that strong earthquakes happen during certain Moon phases has no basis in science, according to new research.
Susan Hough, a scientist at the US Geological Survey, pored over 400 years of data from over 200 earthquakes of magnitude eight or larger. She looked at the day the earthquakes occurred, and what phases the Moon was in. And she found no link between the ground shaking and the position of the Earth and the Moon in the sky, according to a study published this week in Seismological Research Letters.
400 years of data from over 200 large earthquakes
Previous research has shown that tides — which are influenced by the Moon — can nudge faults to unleash earthquakes. “But if you read those papers, you’ll see that the authors are very careful,” Hough said in a statement. “They never claim that the data can be used for prediction, because the modulation is always very small.”
Earthquakes occur because the Earth’s crust is divided into plates. These plates can move smoothly against each other, or become stuck. When they become stuck, they build up strain over time, until one day, the plates unstick, releasing energy that causes an earthquake. Scientists have been trying to predict earthquakes throughout history, but to this day, it’s proven impossible. And that has given rise to several popular beliefs, such as how animal behavior can predict earthquakes. However, anecdotal evidence of weasels and snakes acting weird before the ground starts shaking hasn’t been backed up by science yet (though some researchers are looking into this.)
“Of course, humans are pattern-seeking animals so after the fact we think, oh yeah my dog was behaving weirdly or I noticed, you know, animals got really quiet,” Ned Field, a research geophysicist at the USGS told The Verge last year. “We always remember things after the earthquake, but those could just be random things and nothing has really turned out to be consistently reliable in terms of predicting earthquakes.”
Now, Hough is saying that the phase of the Moon also can’t predict a strong earthquake. In her analysis, Hough didn’t find any kind of pattern that was statistically significant. Her paper reports her findings quite firmly: The headline reads, “Do Large (Magnitude ≥8) Global Earthquakes Occur on Preferred Days of the Calendar Year or Lunar Cycle?” And the abstract simply says, “No.”
So, take her word for it — although Hough isn’t very hopeful. “Sooner or later there is going to be another big earthquake on a full Moon, and the lore will pop back up,” she said. “The hope is that this will give people a solid study to point to.”