Predicting Earthquakes (and the Weather) using the Moon
Is it possible to predict natural phenomena such as earthquakes and weather based on the phase, distance to, and other factors related to the Moon? These sorts of predictions have been around for many years and they do seem to have a certain credibility. The Moon does affect the Earth: we have tides every day and the height of the tides depends on the phase of the Moon, for example at new and full Moon the Sun-Earth-Moon system is roughly lined up so the tides are higher and lower. There is also a tidal effect on the solid land area of the Earth. The Moon warps the Earth's solid surface by about 30 cm at the same time as it creates tides.
So the solid surface of the Earth is being warped by the Moon and that seems like a reasonable possible trigger for earthquakes. If a rock formation was unstable it's reasonable to think that the warping effect of the Moon might be enough to cause an earthquake in that unstable region. But even if it is reasonable, is it true?
The "Moon Man"
As I write this (March 2011) the subject has gained a certain amount of notoriety because Christchurch, a city of about 360,000 here in New Zealand, has recently been hit by two destructive earthquakes and a self-styled expert (see note 1) at predicting earthquakes has suggested there might be another significant event at the next full Moon (in a week on 19 March).
In an interview about his predictions of both earthquakes and weather (see note 2), Ken Ring, the "Moon Man" made this statement: "I do not believe that weather has any chaos in it. The weather knows what it is doing, and as with all the rest of nature is patterned, cyclic, and therefore somewhat predictable to us humans struggling to come up with workable measurable systems."
Almost no credible expert would say there is no chaos involved in weather. Chaos has a specific scientific meaning in this sense (see note 3) and weather prediction is a classic case where the majority of scientists would say that chaos theory applies.
Also, statements like "The weather knows what it is doing" are odd to say the least. Is the weather conscious in some way? And few people would deny that there are patterns and cycles in the weather but these are small compared with unpredictable chaotic effects. As predictions are attempted at greater times in the future (and this is usually just days or weeks at the most) these effects overwhelm the predictable patterns.
In the same interview he claimed to be able to predict earthquakes too. And indeed he did seem to predict some. But earthquakes happen all the time and he makes enough predictions which turn out to be false so this could easily be a case of confirmation bias (see note 4).
There is also this worrying reference to pseudoscience: "The point is, it is possible but it would require cooperation between geologists, astronomers, and probably astrologers, but I doubt that anybody would fund such an enterprise." He wants to involve astrologers in rational, scientific research? That can't be a sign of credibility!
So the issue shouldn't be difficult to resolve. If there is a link between the phase and/or distance of the Moon and the frequency and/or strength of earthquakes then statistics should reveal that correlation. Of course, it's not that easy...
David Winter examined Ring's claims in a recent SciBlogs entry (see note 5). He examined the predictions and found many false positives plus some false negatives indicating confirmation bias is a likely reason for any apparent accuracy. And in a statistical analysis of the Canterbury earthquakes (including many aftershocks) versus Moon phase and earthquakes versus Moon distance he found no or only a very weak (probably insignificant) correlation.
A study published in 2004 (see note 6) did a thorough analysis of the link and concluded that earthquakes fitted a random distribution (so there was no lunar effect). That data set included 3,128 earthquakes in the Pacific Northwest and 4,247 earthquakes in the San Francisco Bay area.
Some studies do suggest a link though. A study published in April 2006 (see note 7) suggested there was a link between micro-earthquakes and the Moon. The study looked for temporal variations during the four-year period following the Kobe earthquake.
The UC Berkeley Seismological Laboratory has done a simple mathematical analysis (see note 8) and concluded from that, and the balance of study results, that there is no significant effect. They said: "Given the relative influence of a planetary alignment and the lack of correlation of earthquakes with the dominant gravitational effects, we would not expect planetary alignments to significantly influence either the rate of occurrence of earthquakes or the relative motion of the tectonic plates. No significant correlations of earthquakes with planetary alignments have been found".
So the evidence is somewhat conflicting but the majority of it seems to indicate either no effect or a very insignificant one. The most important conclusion might be that the relationship, if it really exists at all, is complex and cannot be used as a reliable predictor of when seismic events will occur. And even if predictions based on the Moon were useful (which is far from certain) they should be made by experts in seismology, not enthusiastic amateurs who believe they have discovered something without really testing their conclusions thoroughly.
The bulk of evidence indicates the Moon can't be used to predict earthquakes and a careful analysis of Ring's predictions indicates he's not reliable. But there is a certain credibility to the idea so it can't be judged too harshly. So I give this a moderate score on the crap-ometer!
1. Ken Ring (the "Moon Man") has further information about his controversial ideas (which I think the evidence presented on this page discredits) on predicting weather and earthquakes at the predictweather web site.
2. WeatherWatch interviewed Ken Ring in an article titled "Q&A with controversial 'Moon Man' Ken Ring" which was posted on Wed, 21/04/2010 at 13:00 at WeatherWatch.co.nz.
5. A blog entry critical of Ring's predictions titled "Ken Ring can't predict earthquakes either", by David Winter, was posted on Mar 01 2011, at SciBlogs.
6. A study "Earthquakes and the Moon: Syzygy Predictions Fail the Test" by Matthew Kennedy, John E. Vidale, and Michael G. Parker was published in the UCLA Institute for Geophysics and Planetary Physics Seismological Research Letters, September/October 2004, Volume 75, Number 5, page 607.
7. Correlation between the phase of the moon and the occurrences of microearthquakes in the Tamba region through point-process modeling. Geophysical Research Letters, Vol. 33, L07302, 4 PP., 2006 doi:10.1029/2005GL025510. Takaki Iwata, The Institute of Statistical Mathematics, Tokyo, Japan Hiroshi Katao, Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan.
8. The University of California at Berkeley Seismological Laboratory produced this summary in 1999: Can the Position of the Moon Affect Seismicity?.