Can a Supermoon Trigger Earthquakes? The Truth About Lunar Tides
There's a scene early in the 1994 film Wolf—starring Jack Nicholson and Michelle Pfeiffer—that planted a question in my head I never quite shook. The protagonist gets bitten by a wolf on what the story frames as a "once-in-a-century" night, when the Moon is closer to Earth than it has been in a hundred years. As a kid, I thought it was pure Hollywood magic. As an adult who has spent time reading through NASA orbital data and geophysical studies, I can tell you: that premise is shockingly close to reality. There genuinely are Moon nights that break hundred-year records. And what they do to this planet goes far beyond making a great werewolf movie. If you want more on the kind of invisible physical forces shaping our world, check out our previous post on why convective cooling fails in space.
The Moon's Orbit Is Not What You Think
Most people picture the Moon tracing a clean, circular path around Earth. It does not. The Moon travels an elliptical—oval-shaped—orbit, which means the distance between Earth and the Moon is in constant flux. The far point of this oval is called the apogee. The close point is called the perigee.
Here is where it gets interesting. The shape of that oval is itself unstable. The gravitational tug-of-war between the Sun, Earth, and other planets continuously warps the orbit's eccentricity—its "flatness"—between 0.0255 and 0.0775. Think of it like a hula hoop that someone keeps gently squeezing and releasing. Sometimes the hoop is nearly circular. Other times it stretches into a noticeably narrow oval, pulling the perigee dramatically closer to Earth.
The Moon's phase cycle (synodic month: ~29.53 days) and its perigee-to-perigee cycle (anomalistic month: ~27.55 days) run at slightly different speeds. They drift apart and then realign in a larger master cycle of approximately 414 days. This is why supermoons arrive in clusters of three or four consecutive months rather than every single month.
The Century-Level Close Approach: When the Record Books Open
A "supermoon" happens when the Moon reaches perigee at the exact moment it is also full or new—an alignment astronomers call syzygy. Because the lunar orbit keeps wobbling, not every supermoon is equal. Occasionally, the celestial geometry synchronizes so perfectly that the Moon breaks a multi-decade distance record.
The data from NASA's Jet Propulsion Laboratory tells this story precisely. The closest full Moon of the mid-20th century occurred on January 26, 1948, when the Moon came within roughly 356,460 km of Earth. That record stood for 68 years. On November 14, 2016, the Moon crept to 356,509 km—the nearest it had been in nearly seven decades. And looking forward, November 25, 2034 will produce the next extreme century-level approach, with the Moon reaching just 356,448 km—breaking the 2016 record.
So yes—the "once-in-a-century moon night" that sets off the plot of Wolf is not pure fiction. The astronomical record book genuinely opens and closes on that kind of timescale. What the movie doesn't explain is why a closer Moon isn't just prettier—it is physically more powerful. Gravitational tidal force scales by an inverse-cube law, meaning even a modest drop in distance triggers a non-linear spike in gravitational pull on everything below it.
The Ocean Responds First
The most visible proof of the Moon's power is the tide. When the Moon and Sun align at full or new moon, their combined gravitational pull creates what's called a spring tide—the term "spring" refers to water springing forth, not the season. When that spring tide coincides with the Moon being at perigee, the result is a "perigean spring tide": the strongest astronomical tide of the entire lunar cycle.
NOAA data quantifies the difference: perigean spring tides can push high-water marks 20 to 25 percent higher than a normal spring tide. In concrete terms, that translates to over 30 centimeters of additional sea level rise along typical coastlines. In a place like Anchorage, Alaska—where the funnel-shaped coast already generates tidal ranges exceeding 30 feet—the extra surge during a perigean spring tide can add 3 feet or more on top of an already extreme baseline.
Combine that astronomical surge with rising global sea levels and a seasonal storm, and the risk of catastrophic coastal flooding becomes very real. NOAA classifies water levels just 1.5 feet above the Mean Higher High Water average as "high tide flooding." That threshold gets cleared routinely during a perigean spring tide in vulnerable areas.
The Ground Moves Too
Rock is not rigid—it is elastic. The same lunar gravity that pulls the oceans also rhythmically stretches and compresses the solid crust of the Earth in a process called Earth tides. The ground beneath your feet rises and falls by several tens of centimeters as the Moon passes overhead. Most people never feel it. Fault lines do.
A 2016 study published in Nature Geoscience by seismologist Satoshi Ide revealed a striking pattern. When tidal stress peaked during syzygy, the probability of a small tremor cascading into a massive rupture increased significantly in already-stressed fault zones. The data showed that three of the most catastrophic megathrust earthquakes of the modern era—the 2004 Sumatra quake (M9.0), the 2010 Chile quake (M8.8), and the 2011 Tohoku quake (M9.1)—all occurred near periods of maximum tidal stress.
The scientific community's position is careful but clear: the Moon does not create earthquakes. Tectonic forces are millions of times stronger than any lunar pull. But if a fault has been building stress for centuries and is hovering at the absolute breaking point, the tiny extra gravitational nudge of a supermoon can be the final straw that turns a minor tremor into a catastrophic rupture.
Life Has Been Listening to the Moon for Millions of Years
The Moon's influence does not stop at the ground. Because the atmosphere is a fluid layer of gas, the Moon drags a faint pressure wave through it—a lunar atmospheric tide that alters barometric pressure by about 1.2 to 1.4 hectopascals at the equator. That is tiny compared to a thunderstorm. But it is consistent enough that climate scientists must account for it in long-range global weather models.
More striking is what the Moon has done to animal biology over millions of years of evolution. Every year, tropical coral reefs time their mass-spawning events to the full moon—releasing clouds of eggs and sperm simultaneously to maximize fertilization while overwhelming predators with sheer abundance. Laboratory studies have shown that some marine species maintain this lunar spawning rhythm even in windowless tanks, with no access to moonlight or tidal cues. The clock is encoded in their DNA.
In the skies, a study in PLoS Biology tracked the European nightjar and found that its foraging activity more than doubled under a bright full moon, after which up to 100 percent of tracked birds launched simultaneous migratory flights. The Moon did not just influence migration—it commanded it. Meanwhile, at the bottom of the food chain, ecological surveys in South Africa found that small rodents dramatically reduced their activity during full moon nights. The bright light helps predators. Prey animals have evolved to simply disappear during it.
Frequently Asked Questions
Does a truly "once-in-a-century" supermoon actually exist, or is it just movie fiction?
It is real. NASA tracking data shows that record-breaking lunar close approaches—where the Moon breaks a multi-decade distance record—occur on roughly century-long timescales. The 1948 record stood 68 years before 2016 broke it. The 2034 close approach will break it again. The Wolf movie's premise is scientifically grounded in a way most viewers never realize.
Can a supermoon actually trigger a major earthquake?
The scientific answer is "conditionally." Research published in Nature Geoscience shows that lunar tidal stress can increase the probability of a small earthquake escalating into a major rupture—but only in specific geological environments like subduction zones. The Moon cannot create an earthquake where the stress has not already built up over centuries. Strike-slip faults like California's San Andreas appear largely unaffected.
Why do some animals seem to behave strangely during a supermoon or full moon?
Because millions of years of evolution have hardwired the lunar cycle into their biology. Coral species maintain an internal "circalunar clock" that triggers mass spawning even in laboratory settings without any moonlight. Migratory birds use the bright full moon as a fuel and launch signal. Prey mammals suppress their foraging entirely during bright lunar phases to avoid predators. The Moon is not just an astronomical object for them—it is a survival calendar.
Sources & References
NASA Jet Propulsion Laboratory — Lunar Ephemeris & Orbital Data
NOAA — Perigean Spring Tides & High Tide Flooding Data
Ide, S. et al. (2016). "Earthquake potential revealed by tidal influence on earthquake size-frequency statistics." Nature Geoscience.
Scholz, C. et al. (2019). "Tidal modulation of earthquake activity." Nature Communications.
Dominoni, D. et al. "Lunar cycles drive migration of a nocturnal bird." PLoS Biology.
For more on the invisible physical forces that shape our world, visit www.thesecom.com.
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