Seismo Lab Brown Bag Seminar

Ghost stories abound in the Charleston, South Carolina, region. Among them, the legend of the Summerville Light, or Summerville Ghost, holds that a strange ball of light sometimes seen in a remote area is a lantern carried by the ghost of a bereaved woman, who in life waited for her husband to return from his railroad job, only to learn that he been killed that day in an accident, only his headless body recovered. The grieving widow is said to return after her own death, still searching for her husband's remains. I consider this tale in the context of a newly developed paradigm to explain the 1886 Charleston earthquake and Charleston seismic zone. I suggest that many if not all of the ghostly manifestations can be readily attributed to natural earthquake processes including earthquake lights. Of the theories proposed to explain earthquake lights, mechanisms involving shallow gas release from shallow faults provide the most obvious explanation for the Summerville Light, either ignition of flammable gases such as methane or sulfur gases, or discharge from electrons moving from excited to ground states. Accounts of sulfur smells abound in the Summerville area, including reports of strong odors following one of the larger foreshocks of the 1886 mainshock. Ghosts with lanterns are said to wander along railroad tracks in other regions, searching for lost heads, often on dark and misty nights. The similarity of the legends suggests a set of conditions under which earthquake lights can be generated, including the presence of railroad tracks to which bereaved ghosts are apparently partial. I suggest that friendly ghosts may thus help illuminate not only active shallow faults in low-strain-rate regions, but also earthquake and/or fault processes involving gas release. I discuss ways that this creepy and kooky hypothesis might be testable.