One of the most famous sightings of the Marfa lights occurred in 1973 when two geologists, Elwood Wright and Pat Kenney , observed two lights and tried to track them down. At first they used a jeep, then later proceeded on foot. They never caught up with them, but the scientists were left with the unnerving impression that the lights were toying with them. Although these represent some of the most active locations, reports of lights like this have been cataloged from almost a hundred different areas within the United States alone. Many additional reports have come from locations around the world.
Some scientists suggest that it is seismic activity.
Many of these locations are in geologically unstable regions with faults. Faults are fractures in the earth's crust that may shift during earthquakes or tremors. It may be that the lights are the result of static electric charges that build up as rock moves against rock underground. Some spook lights have actually been seen during violent earthquakes, but most would have had to been generated by movements in the faults too small to been noticed. It may also be possible that there is no one single explanation for spook lights, but that there are a variety of causes.