Summerville, a town northwest of Charleston, S.C., has its share of ghost stories. One yarn that has stuck around for decades is the tale of the Summerville Light.
In the dead of night, along a dirt road in the nearby pine forest following abandoned railroad tracks, people have observed mysterious lights, bobbing up and down, pulsing with a pale blue, green or orange hue.
Along the tracks, the story goes, a woman waited for her husband, a railroad worker, to return. But he died, losing his head in an accident. Ever devoted, the widow searched for his remains. She continued — even after her own death: The flicker of her lantern was all that remained.
It’s a goose-bumpy explanation of the Summerville Light. The remote road in the story even became known to locals as Light Road, a spot where specter seekers reported glowing orbs and unusual noises in the 1960s.
Susan Hough, a seismologist at the U. S. Geological Survey, thinks this supernatural story can be explained by natural phenomena. While studying the area’s seismology, Dr. Hough scoured historical accounts, old newspaper articles, letters and diaries for mentions of earthquakes. One book she found, “Haunted Summerville,” mentioned a big 1886 quake. Could there be a connection between earthquakes and the area’s ghost stories?
Some reports of the Summerville Light also mentioned that cars violently shook. “Well, to a seismologist, that sort of screams ‘shallow earthquake,’” Dr. Hough said.
She reckoned that some reports of paranormal activity might be explained by earthquakes. In a house that hosted a tearoom and antiques shop, the owners described noises upstairs, doors slamming and objects that had been moved. Those observations echo how seismologists describe the results of certain low-level seismic activity.
“It’s basically shaking that’s at the threshold of perceptibility,” she said.
Though far from the edge of a tectonic plate, Summerville has seen major shaking. The big 1886 earthquake caused serious damage in Charleston, Dr. Hough said. But that temblor’s epicenter was closer to Summerville, she said. To better understand the area’s seismic risks, Dr. Hough and her colleagues have been studying its faults, a difficult task as they lie buried under swampy sediments.
Historical sources have provided hints. An account of the 1886 event described how a railroad line south of Summerville had been yanked to the right by around 15 feet. That confirmed that a fault must run right through there, Dr. Hough said. The area is still seismically active, at a low level, but elevated compared with other places along the East Coast.
But what about the ghostly lights?
Summerville was jolted by at least three earthquakes in 1959 and 1960. And seismic rumblings can produce mysterious glows known as earthquake lights.
In 2014, researchers examined reports on dozens of earthquakes and their luminous glows and found some trends. Earthquake lights tended to arise from quakes far from the edges of plates, in areas that have been stretched out and in places with rocks relatively rich in iron and magnesium. The Charleston area checks those boxes. “The ingredients are all there,” said Will Levandowski, a geophysicist at the consulting company Tetra Tech who was not part of the study. He added that it is “an appealing explanation for these ghost stories.”
Researchers have come up with several hypotheses for earthquake lights. One says that, in the lead up to shaking, minerals within the earth deform, freeing up electrical charges. These charges can travel to the surface, where they create electrical fields strong enough to make molecules in the air glow.
Another explanation involves gases, like methane, released by earthquakes. Friction, such as that from seismic motion, can create static electricity, said Yuji Enomoto, who studies earthquake science and disaster prevention at Shinshu University in Japan and was not involved in the work. The buildup of charge can provide the spark to combust the methane, producing colored light, including blue and orange hues. Radon gas, which is released along active faults, may also play a role.
In Summerville, the old rail lines or debris left around the track could have been rubbing together to provide a spark for the lights, Dr. Hough noted in a paper she published last week in Seismological Research Letters.
“It hangs together in the sense that the ghosts are hanging out near Summerville,” Dr. Hough said. “And, by all indications, Summerville was kind of ground zero — where the strongest shaking occurred.”
Summerville’s widow isn’t alone in haunting rail lines.
“When you start to look around, it turns out there’s quite a few ghosts wandering around railroad tracks,” Dr. Hough said.
A story from Maco, N.C., that may predate Summerville’s seems curiously similar: It’s about another railroad worker who searches for his own lost head. Maco, near Wilmington, N.C., is in a seismically active area that has some similarities to Charleston. Perhaps places where apparitions are said to appear may reveal low-level seismic activity that has gone unnoticed.
A highway offramp now blocks the stretch of Light Road where the lights were reported. But maybe, when the ground trembles, the ghostly gleams still visit the pine forest.