Mystery AtlasAre Earthquake Lights Real, and What Causes Them?
Last updated 20 August 2026 · 6 min read
Direct Answer
Earthquake lights, brief flashes, glows, or streamers reported in the sky around the time of an earthquake, are a real, documented phenomenon, though a genuinely rare one, occurring in an estimated fewer than 0.5 percent of earthquakes. A 2014 peer-reviewed catalogue study examined 65 of the best-documented historical cases and found about 85 percent occurred near tectonic rifts and 97 percent near a subvertical fault, supporting physicist Friedemann Freund's peroxy-defect theory, in which mechanical stress on certain rock types releases an electric charge that can produce visible light. The theory remains actively debated rather than fully confirmed, and individual modern video clips are frequently disputed, since ordinary sources such as arcing power lines and exploding transformers can produce visually similar flashes during an earthquake's ground shaking.
Background
Reports of unusual lights in the sky around the time of an earthquake stretch back centuries, appearing in accounts from ancient Greece through medieval Europe to the present day, but the phenomenon remained largely anecdotal and scientifically unexamined as a coherent category until relatively recently. Witnesses have described sheet-like glows, discrete floating balls of light, narrow beams or streamers, and steady luminous hazes, usually white, blue, or violet in colour, occurring in the minutes surrounding an earthquake's ground shaking.
The most significant systematic study of the phenomenon, published in January 2014 in the peer-reviewed journal Seismological Research Letters by Robert Thériault, France St-Laurent, physicist Friedemann Freund, and seismologist John Derr, combed centuries of documented reports and discarded cases with plausible non-seismic explanations, such as ground smoke or lunar halo effects, to arrive at 65 of the best-documented earthquake-light cases across the Americas and Europe since 1600. The study found that approximately 85 percent of these cases occurred near tectonic rifts, and 97 percent, 63 of the 65 cases, occurred adjacent to a subvertical fault, a rift, graben, strike-slip, or transform fault.
Modern video technology has produced some of the strongest individual pieces of evidence. Security-camera footage from Pisco, Peru, recorded bright sky flashes moments before the magnitude 8.0 earthquake that struck the region in August 2007, and similar green and blue lights were filmed during a magnitude 8.1 earthquake affecting Mexico in September 2017. Not every widely circulated video has held up under scrutiny, however: footage from the 8 September 2023 magnitude 6.9 Al Haouz earthquake in Morocco, showing blue flashes over the city of Agadir, was extensively shared online as a possible earthquake light but has also been explained by many analysts as electrical arcing from power lines and exploding transformers damaged by the shaking, illustrating how genuinely difficult it can be to distinguish a real earthquake light from an ordinary infrastructure failure occurring at the same moment.
Main Theories
The peroxy-defect theory
Friedemann Freund's peroxy-defect theory, the mechanism most cited by researchers who accept earthquake lights as a genuine geophysical phenomenon, holds that certain volcanic rock types, particularly basalt and gabbro, contain microscopic peroxy defects, oxygen atom pairs bonded together in a way that is chemically unstable. Under the intense mechanical stress that builds before and during an earthquake, these defects can break apart and release mobile electronic charge carriers, effectively turning a stressed rock formation into a natural battery. Freund and colleagues have argued that under the right conditions, this charge can travel through the rock and discharge at the surface as visible light, in a process some researchers have compared to "switching on a battery in the Earth's crust." The 2014 Thériault, St-Laurent, Freund, and Derr catalogue study's finding that documented cases cluster overwhelmingly near rifts and subvertical faults is presented as supporting evidence, since these are precisely the geological settings where peroxy-defect-bearing rock types and efficient charge pathways are most likely to coincide.
Sceptical and alternative explanations
The United States Geological Survey maintains an officially cautious position, noting that geophysicists differ on how many individual light reports genuinely represent a distinct seismic phenomenon rather than misidentified ordinary events. Sceptics point out that earthquakes routinely damage electrical infrastructure, and arcing power lines, exploding transformers, and other electrical failures can produce sky flashes visually similar to reported earthquake lights, a concern the disputed 2023 Morocco footage illustrates directly. Other proposed physical mechanisms include a piezoelectric effect in quartz-bearing rocks, which can generate strong electric fields when compressed in specific crystallographic orientations, and a 2014 Rutgers University laboratory study finding that agitated granular materials can produce voltage spikes through inter-particle friction alone, a more general mechanical explanation that does not require Freund's specific peroxy-defect chemistry.
Common Misconceptions
A common misconception holds that earthquake lights are now a scientifically settled phenomenon with an agreed cause. The peroxy-defect theory is the leading and most peer-reviewed explanation, but it remains actively debated rather than universally accepted, and the US Geological Survey's own public guidance stops short of formally endorsing it as the confirmed mechanism.
A second misconception treats every viral video showing sky flashes during an earthquake as confirmed footage of the phenomenon. As the disputed 2023 Morocco footage shows, electrical infrastructure failures triggered by the same shaking that causes a genuine earthquake light can produce visually similar flashes, and distinguishing the two after the fact, without instrumental data beyond a video recording, is often genuinely difficult.
Current Consensus
Earthquake lights are increasingly accepted within seismology as a real, if rare, documented phenomenon rather than folklore, a shift driven substantially by the 2014 Thériault, St-Laurent, Freund, and Derr catalogue study and by an expanding body of modern video evidence from smartphone and security cameras. The peroxy-defect theory is the leading mechanism cited in the peer-reviewed literature, but the United States Geological Survey and many seismologists maintain that individual reports require careful case-by-case evaluation, since electrical infrastructure damage remains a genuine competing explanation for many modern video clips, and the underlying physical mechanism, while increasingly well-supported statistically, has not been directly observed occurring in controlled laboratory conditions at the scale of a real fault.
Why This Mystery Endures
Earthquake lights occupy an unusual position among this site's scientific-frontier subjects: a phenomenon with a serious, published, peer-reviewed mechanism and a genuine statistical pattern behind it, yet one still routinely entangled with ordinary explanations in any individual case, much the way ball lightning remains scientifically real in aggregate while any single reported sighting is difficult to verify against mundane alternatives. That combination, a phenomenon statistically well-supported but individually hard to confirm, is precisely the condition that keeps a real, published scientific question alive in public fascination well beyond the seismology literature that actually studies it.
The phenomenon's rarity also plays a role: because earthquake lights appear in an estimated fewer than 0.5 percent of earthquakes, most seismologists, let alone the general public, will never personally witness one, leaving the subject dependent on a relatively small, slowly growing body of historical accounts and modern video evidence rather than routine, repeatable observation. Each major earthquake with viral camera footage, from Pisco in 2007 to Morocco in 2023, renews public interest and debate, giving the phenomenon a steady stream of new candidate evidence even as the underlying scientific question, precisely which cases are genuine and which are electrical coincidence, remains only partially resolved.
Frequently Asked Questions
- What do earthquake lights actually look like?
- Reported forms vary considerably across documented cases: witnesses describe sheet-like glows spread across the sky, discrete floating balls of light, narrow streamers or beams, and a steady ambient luminance, most commonly in shades of white, blue, or violet. This variability is itself one reason the phenomenon has been difficult to study systematically, since researchers cataloguing historical reports must first judge which accounts describe a genuinely consistent phenomenon rather than several unrelated effects grouped together after the fact.
- Has a genuine earthquake light ever been captured on video?
- Security-camera footage from Pisco, Peru, showed bright sky flashes shortly before the magnitude 8.0 earthquake there in August 2007, widely cited as one of the clearest modern video records. Footage from an earthquake in Mexico in September 2017 similarly showed green and blue lights during a magnitude 8.1 event. Not every viral video is accepted as genuine: footage from the 8 September 2023 Al Haouz earthquake in Morocco showing blue flashes over Agadir was widely shared as a possible earthquake light, but many analysts concluded the bursts more closely matched electrical arcing from damaged power infrastructure and exploding transformers during the shaking, a mundane explanation that competes directly with the earthquake-light interpretation in exactly these kinds of urban, camera-rich modern cases.
- Why don't earthquake lights happen at every earthquake?
- Under the peroxy-defect theory, the effect depends on specific rock chemistry, certain volcanic rock types such as basalt and gabbro that contain enough peroxy defects, oxygen anion pairs bonded in a way that can release an electric charge under mechanical stress, and a fault geometry, chiefly subvertical faults near rifts, that channels that charge efficiently toward the surface. Most earthquake zones and fault types do not have both ingredients together, which the 2014 catalogue study's finding, that documented cases cluster overwhelmingly near rift environments, is offered as evidence for.
- Do earthquake lights predict earthquakes before they happen?
- Some historical accounts describe lights appearing minutes or even hours before the main shock, which has fed occasional interest in the phenomenon as a possible short-term earthquake precursor. However, the reported timing is inconsistent across cases, some lights are reported during or shortly after the shaking rather than before it, and no scientific body currently endorses earthquake lights as a reliable predictive signal; the United States Geological Survey and most seismologists treat the phenomenon as a subject worth documenting after the fact rather than as a forecasting tool.
References
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