From around the mid-20th Century CE, people have told stories of a ghost haunting the railroad track between Charleston and Summerville in South Carolina. Though there are a number of versions of the story, as will happen with folklore, the story generally goes like this: A man either working on the railroad, or sometimes just traveling upon it, was hit by a train and killed, and/or decapitated. It’s not the man who is said to haunt the railway lines, but his wife.

“As the story goes, through the rest of her life and even after her own death, the distraught wife was said to return to the tracks with a lantern, searching for her husband’s remains,” Dr Susan Hough explains in her new paper.

Throughout the 1950s and 60s and beyond, there have been a number of strange sightings on a nearby road parallel to the railway tracks, with witnesses reporting strange lights seemingly floating in the air. Eventually, the road known as Old Sheep Island Road became known locally as Old Light Road, and became an attraction for ghosthunters and the like.

Accounts of the lights generally describe them as small, ball-shaped, and blue or green in color, though sometimes red or white balls have been witnessed. While generally the lights are seen some distance away, occasionally they have been witnessed as rushing towards the observer, or sometimes are seen to grow in size. One account puts the lights as basketball-sized, and hovering in mid-air for several minutes.

On top of this, sightings of ghosts have been reported in nearby houses and establishments, as well as other odd occurrences such as cars shaking, doors slamming, and whispered voices being heard without a source.

While it would be easy to dismiss these accounts as mere ghost stories, passed on and made more elaborate, looking through the accounts, Hough found reasons to believe there may be a common, geological thread.

The shaking of the cars, for example, could be put down to earthquakes with a shallow source. The glowing orbs, far from being a lantern carried by a ghost, could be “earthquake lights”. Though there is no single accepted theory on what causes them, there are a few ideas. One is that they are caused by gas release from the Earth.

“The gas release hypothesis involves two possible mechanisms,” Hough explained to IFLScience. “As an inert gas, radon will not ignite, but could potentially be associated with a glow discharge phenomenon, whereby electrons move to an excited state and then fall back to their ground orbital shell. This usually happens at low temperatures, close to the freezing point. Enomoto (2024) presents other ideas, involving gamma rays in the atmosphere, and radon or radon/methane gas release.”

Alternatively, the gas release hypothesis suggests that they could be caused by the ignition of flammable gasses as they are exposed to oxygen.

“The association between ghosts and railroad tracks made me think about sparks,” Hough continued. “But the association could have a different explanation, for example the tendency of railroads to follow corridors that were carved out by faults.”

As for the noises heard by locals of the area, this could come down to high-frequency shaking noises resulting from tremors. It is not the first time that ghostly apparitions have been put down to sound.

“Sound waves at frequencies of 20–200 Hz are within the audible range,” Hough writes in her study. “Studies further suggest that infrasonic noise, that is, at frequencies lower than 20 Hz, may cause noticeable sensations. Felt foreshocks of the 1886 Charleston earthquake, for example, were sometimes reported as “detonations”, suggesting high-frequency energy from a shallow, nearby source.”

Hough began the project while looking into the 1886 earthquake, and more generally the Charleston Seismic Zone, before being inspired by a “spooky science” newsletter at the USGS to look into these ghost stories further. However, the work may end up helping geological research, as well as explaining some pretty odd apparitions.

“The study felt too frivolous for words when I started, but could actually help address a difficult and important problem: which of the many preexisting faults in the east (and elsewhere) are active? Are there more potential seismic zones than the small handful that have produced large earthquakes during the short historic record?” Hough told IFLScience.

“My hope is that ghost stories might provide a useful target for investigations, both to understand earthquake lights, and to identify shallow active faults in eastern North America.”

The study is published in Seismological Research Letters.