Do Supermoons and Full Moons Trigger Major Earthquakes? A Look at the Data
By Shayne Heffernan
For centuries, people have wondered if the moon’s cycles—especially supermoons and full moons—play a role in triggering earthquakes. A supermoon happens when the moon is at its closest point to Earth during a full moon, exerting a stronger gravitational pull, while a full moon alone still creates significant tidal forces. These forces are known to affect ocean tides, so it’s natural to ask if they might also influence the Earth’s crust, particularly along high-risk fault lines near major cities like Bangkok, Tokyo, Los Angeles, and San Francisco. As a financial analyst with a keen interest in global phenomena, I’ve dug into recent earthquake data to explore whether there’s a real correlation between lunar phases and seismic events above magnitude 7.0. Let’s examine the evidence and consider the risks for these vulnerable urban centers.
Earthquake Data and Lunar Phases
To investigate, I looked at earthquakes of magnitude 7.0 or greater from the past decade, focusing on their dates and the corresponding lunar phases. Here’s what the data shows:
- March 11, 2011: Tohoku-Oki Earthquake, Japan (Magnitude 9.0)
This devastating quake struck off the coast of Japan, triggering a massive tsunami. It occurred during a neap tide, a period of lower tidal stress between a full and new moon, but tidal stress was still high due to the moon’s gravitational pull. Researchers at the University of Tokyo noted that this event happened near a time of elevated tidal stress, though not during a full moon or supermoon. - February 27, 2010: Maule Earthquake, Chile (Magnitude 8.8)
This powerful earthquake hit Chile during a full moon, which coincided with a spring tide—a time of maximum tidal stress when the sun and moon align to exert the greatest gravitational influence on Earth. The timing suggests a possible link to lunar forces. - December 26, 2004: Sumatra Earthquake, Indian Ocean (Magnitude 9.1–9.3)
Known for its catastrophic tsunami, this quake occurred near a full moon and during a spring tide, again aligning with a period of high tidal stress. Researchers have pointed to this event as one where lunar influence might have played a role. - July 27, 2022: Northwestern Luzon Earthquake, Philippines (Magnitude 7.0)
This quake struck the Philippines, with its epicenter 15 km deep. It occurred just after a new moon, another period of high tidal stress, though not a supermoon. The event caused significant damage, affecting over 574,000 people. - March 28, 2025: Myanmar Earthquake (Magnitude 7.7)
A recent and devastating quake hit near Mandalay, Myanmar, along the Sagaing Fault. It occurred three days after a new moon on March 25, 2025, during a period of elevated tidal forces. The shallow depth of 10 km amplified its impact, causing widespread damage as far as Bangkok, over 600 miles away. - December 5, 2024: Ferndale Earthquake, California (Magnitude 7.0)
This quake struck near Ferndale, just west of the Mendocino Triple Junction in California. It occurred one day after a full moon on December 4, 2024, aligning with a period of strong tidal forces. The U.S. Geological Survey deployed seismometers to study its aftershocks.
Analyzing the Correlation
The data shows a mixed picture. Some major earthquakes—like the 2010 Maule quake and the 2004 Sumatra quake—occurred during or near a full moon, when tidal stress is at its peak. Others, like the 2011 Tohoku-Oki quake, happened during high tidal stress but not precisely on a full moon or supermoon. The 2022 Luzon quake and the 2025 Myanmar quake also align with periods of elevated tidal forces, though not supermoons. The 2024 Ferndale quake, however, directly followed a full moon, adding to the pattern.
However, not all large earthquakes fit this trend. A 2018 study by U.S. Geological Survey seismologist Susan Hough examined over 200 earthquakes of magnitude 8 or greater over four centuries and found no significant correlation between lunar phases and seismic events. She noted that the timing of these quakes was essentially random with respect to the moon’s cycle. Other studies, like one by Satoshi Ide and colleagues at the University of Tokyo, found that very large earthquakes (close to magnitude 9) tend to occur near times of maximum tidal stress, but the relationship isn’t consistent across all events.
The science suggests that while the moon’s gravitational pull can slightly influence faults—potentially acting as the “straw that breaks the camel’s back” for a fault already close to slipping—the effect is small and not reliable for prediction. Tidal forces may modulate earthquake rates slightly, but they don’t directly cause them. Many large quakes, like those in November 2006 and January 2007, showed no correlation with lunar phases.
High-Risk Fault Lines and Major Cities
The potential for lunar influence, however small, becomes more concerning when we consider high-risk fault lines near major cities. These urban centers are densely populated and often have infrastructure that may not be fully prepared for a major quake.
- Bangkok and the Sagaing Fault
The Sagaing Fault runs through Myanmar, a boundary between the Burma and Sunda plates, and is one of the world’s most seismically active regions. The recent magnitude 7.7 earthquake on March 28, 2025, caused a high-rise building under construction in Bangkok to collapse, despite being over 600 miles from the epicenter. Bangkok’s geology, with its soft marine clay layer, amplifies long-period ground motion, making tall buildings vulnerable to distant quakes. Seismic building codes were only introduced in 2007, leaving older structures at risk. - Tokyo and the Subduction Zones
Tokyo sits near the convergence of the Pacific, Philippine Sea, and Eurasian plates, a region prone to subduction zone earthquakes. The 2011 Tohoku-Oki quake, with a magnitude of 9.0, occurred in this zone, killing thousands and causing a devastating tsunami. Japan experiences frequent seismic activity, and while the 2011 quake happened during high tidal stress, the correlation isn’t definitive. Tokyo’s modern infrastructure is better prepared, but the risk remains high due to its location. - Los Angeles and the San Andreas Fault
Los Angeles is located near the San Andreas Fault, a strike-slip fault where the Pacific and North American plates slide past each other. The U.S. Geological Survey estimates a 46% chance of a magnitude 7.0 earthquake in the Los Angeles region within the next 30 years. A 2016 study found that low-frequency earthquakes along the San Andreas were more likely during the moon’s waxing phase, but this applies to smaller events, not necessarily major quakes. Los Angeles has invested in seismic upgrades, but a major quake could still cause significant damage. - San Francisco and the Hayward Fault
San Francisco lies along the Hayward Fault, part of the San Andreas system, which is among the most active and dangerous in the U.S. The USGS gives a 51% chance of a magnitude 7.0 quake in the San Francisco Bay Area within the next 30 years. The 2024 Ferndale quake, occurring just after a full moon, serves as a reminder of the region’s vulnerability. Like Los Angeles, San Francisco has made strides in earthquake preparedness, but its dense population and older buildings remain at risk.
What This Means for the Future
The data suggests that while some major earthquakes align with full moons or periods of high tidal stress, the correlation isn’t strong enough to predict seismic events. The moon’s gravitational pull may play a minor role in triggering quakes along faults already primed to slip, but it’s not a primary cause. For cities like Bangkok, Tokyo, Los Angeles, and San Francisco, the real concern isn’t the moon—it’s their proximity to active fault lines and the state of their infrastructure.
Bangkok’s recent experience with the Myanmar quake highlights the need for stricter building codes and better urban planning in Southeast Asia. Tokyo, Los Angeles, and San Francisco, while better prepared, still face significant risks due to their locations on major fault lines. The U.S. Geological Survey notes that 75% of the U.S. is at risk of damaging earthquakes, with California cities among the most vulnerable.
As I see it, the focus should be on preparation, not lunar cycles. Strengthening buildings, improving early warning systems, and educating communities in these high-risk areas will do far more to save lives than trying to predict quakes based on the moon. The Earth’s crust will move when it’s ready—whether the moon is full or not.
Shayne Heffernan is a financial analyst and the founder of Knightsbridge, a global investment firm. With over 40 years of experience, he closely monitors economic trends and global phenomena.
