Can the Moon Make an Earthquake Worse?

By Nathaniel Scharping | September 12, 2016 4:13 pm

(Credit: Danshutter/Shutterstock)

When an earthquake occurs, it represents the release of years, sometimes decades or centuries, of pent-up stress. Somewhere along the fault line, a section of rock can take the strain no longer and gives way, allowing a tectonic plate to jerk into motion in a series of spasmodic shudders.

The factors that determine when, where and why earthquakes happen are numerous, and we’re still a long way from figuring out how to reliably predict them. But, it turns out that one of the many small stresses leading up to an earthquake may be extraterrestrial.

Moon Pushes and Pulls

In a study published Monday in Nature Geosciences, a team of Japanese researchers say that they have found a statistical correlation between periods of excessive tidal forces and large earthquakes.

The tides, of course, are a consequence of the moon’s gravitational tug. As it orbits the Earth, the moon pulls a small bulge of water with it, sloshing the oceans back and forth. And, just as the oceans move with the moon, so too does the land. The Earth’s crust actually moves by about a foot every day due to the motion of the moon, a so-called “land tide.”

The subtle flexing of the Earth’s crust could be another factor in determining when the critical points along fault lines give way. As the moon tugs on the rock, it could provide that final nudge that sets a cascading series of larger slips into motion, creating an earthquake.

The researchers say that several major earthquakes in recent history happened during full or new moons, when the sun, Earth and moon line up, and tidal stress is at its highest. In addition, the ratio of large earthquakes to smaller temblors appears to increase during that time.

Interestingly, however, there appears to be no correlation between tides and smaller earthquakes — the relationship only holds for the largest rumbles.

In all, nine of the 12 biggest quakes on record happened near new or full moons, a number that appears to exceed chance. This included the 2004 Indonesian earthquake and ensuing tidal wave, and the 2011 earthquake in Japan that caused the Fukushima nuclear disaster.

Old Idea, New Analysis

The idea that the moon’s gravitational tug may kickstart earthquakes is not new. The researchers cite papers going back to the 19th century that examined the link between lunar cycles and earthquakes.

More recently, a paper from researchers at the U.S. Geological Survey found that a specific kind of deep earthquake at the San Andreas fault was more likely to occur when tidal forces were increased during the two-week fortnightly tide cycle. Scientists have never been able to find any conclusive evidence of a link, however.

Both papers stop far short of saying the Moon is causing earthquakes, though. Instead, it seems that the tidal forces the moon exerts may cause what could have been a small quake to grow much larger.

The mechanism by which this happens is still unclear, however. Tidal forces are just one of many, many factors all working together to push, pull and twist the Earth’s crust, all of which combine to occasionally produce a quake. Somewhere along that chain of events, the moon could provide the extra nudge needed to set the earth in motion.

Knowing that the movements of the moon affect how earthquakes happen gives us a better idea of when and where they’ll strike.

CATEGORIZED UNDER: Environment, top posts
  • joseph2237

    Land tide are more like heat expansion. if they were as deep as the crust we would be able to predict earth quakes every day,

  • Uncle Al

    The US has major earthquake concerns (Cascadia, Oklahoma, New Madrid). The 21 August 2017 total solar eclipse spans the US near all three areas. Why isn’t NASA planning fundamental definitive gravitational measurements under the path of totality re the controversial Allais effect on Foucault, paraconical, and torsion pendulums plus gravimeters?

    What will NASA do, plausibly deny responsibility when physical reality dumps on political connivance? “That was not the solution we were seeking.”

    • the_misadventures_of_bunjee

      I think Uncle Al needs to lay off the sauce.

  • OWilson

    “The idea that the moon’s gravitational tug may kickstart earthquakes is not new”

    I suggest that “kickstart” is an inappropriate word. More like a tipping point phenomena, a “last straw”.

    If the Moon’s gravity can deform the Earth’s crust by a foot every day, they have their answer.

    Whether this or that specific straw (tidal effect) triggers the movement depends on the inherent and growing potential instability of the system as a whole.

  • jonathanpulliam

    Lobbyists for fracking will play up the lunar angle, while NASA fiddles Nero-like as the Earth’s magnetic polarity swaps

  • Mr Kennedy

    To my Japanese friends… Look to the heavens above and beyond the moon and ye shall find a more convincing and full correlation. Just take into account Jupiter and Saturn…for instance then add the other planets one by one. Don’t think of the weak gravitational waves as of little consequence… there is surely an alignment influence like those of magnets which may cause an amplification scenario. Gravitational waves after all are caused by rapid movement which cause distortion or ripples in space time… is there a “overlapping harmony effect” in certain alignments? The sun travels at x kmh and has a mass of ? much faster than our fastest space shuttle (allegedly). The planets travel at ? kmh and are of mass ?.
    Einstein proved that gravitational waves exist back in 1916. We can only measure them since around 1960 (and not very well) Also we are not so interested in our planets gravitational waves but rather of black holes & pulsing things at least in our galaxy.
    Is there magma under the Earth’s crust?
    Is it solid, liquid or molten? Does the Moon influence the molten lava like the oceans above? Do they also have tides? Do volcanoes erupt more often at high tides or full / new moons?
    Now we need to understand where the fault lies. Quite easy! But when? This is the true dilemma. Do we need to know when an earthquake of less than 4.5 will strike? It depends… If one man dies is it not too many? What are the statistics on earthquake deaths? Is it ok to leave these questions unanswered?
    Take my advice look to the heavens and you will find the answers.
    PS: There is a significant influence of the delta angle between Jupiter and Saturn with respect to the Earth and major earthquakes in Italy (at least since 1976).
    Perhaps “Gravitational Wave Resonance”? Did Einstein directly or indirectly predict earthquakes?


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