For decades, witnesses in a small South Carolina town have reported blue-green orbs drifting along abandoned railroad tracks—lights that hover, grow to basketball-size, and sometimes rush toward the terrified observer. Local legend says it's the ghost of a grieving widow, searching with her lantern for her husband's remains after he was killed by a train. But a USGS seismologist has proposed something stranger than any ghost story: the lights might be earthquake lights, generated by seismic stress in one of the most earthquake-prone regions of the Eastern United States.