Can A Full Moon Trigger California's 'Big One'?

Scientists and non-scientists alike have heard about it. The Big One. The disastrous earthquake that's bound to strike along California's infamous San Andreas fault. Of course the question on everyone's minds is: When?

Unfortunately, this is not a question that can be answered with any absolute certainty, but that doesn't mean we can't try to find some clues along the way.

The latest theory suggests that a strong earthquake may happen during a full moon, due to high tidal stresses. Results of a new study by Satoshi Ide, a seismologist at the University of Tokyo, were published this week in the international journal Nature Geoscience.

"Earth’s tides, which are caused by a gravitational tug-of-war involving the Moon and the Sun, put extra strain on geological faults," a summary of the study says on Nature's website. "Seismologists have tried for decades to understand whether that stress could trigger quakes. They generally agree that the ocean’s twice-daily high tides can affect tiny, slow-motion tremors in certain places, including California’s San Andreas fault and the Cascadia region of the North American west coast."

Ide and his team came up with a system of ranking "tidal stress," with 15 being the highest, and compared that information to large earthquakes on record. They soon discovered that of 12 of the biggest quakes on record— 9 of them happened on new or full moons, according to USA Today.

"They found that large quakes such as those that hit Chile and Tohoku-Oki occurred near the time of maximum tidal strain — or during new and full moons when the Sun, Moon and Earth align," Nature's site says. "For more than 10,000 earthquakes of around magnitude 5.5, the researchers found, an earthquake that began during a time of high tidal stress was more likely to grow to magnitude 8 or above."

But just because this study suggests we may need to drop, cover and hold on on a full moon, seismologists remind us that there are countless more factors that need to be taken into account.

University of Washington Seismologist John Vidale offered some insight on the findings to USA Today, saying that "...even if there is a strong correlation of big earthquakes with full or new moons, the chance any given week of a deadly earthquake remains miniscule."

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