ts. “The numbers are stratement. ”We don’t know quite yet why more earthquake light events are related to rift environments than other types of faults, but unlike other faults that may dip at a 30-35 degree angle, such as in subduction zones, subvertical faults characterize the rift environments in these cases.” Two of the 65 documented EQL cases that researchers studied are associated with subduction zones, but Thériault posits there may be an undiscovered subvertical fault present. Eighty-five percent of the 65 earthquakes were greater than M 5.0. The EQL differed in shape and extent, though most frequently appeared as globular brilliant

Rare ‘earthquake lights’ linked to rifts in Earth

EQL can look like spheres of light floating through the air.

According to a news release from the Seismological Society of America, rare earthquake lights (EQL) are more likely to take place on or near rift environments, where subvertical faults allow stress-induced electrical current to travel rapidly to the surface. Interestingly, EQL appear before or during earthquakes, but seldom after.
EQL can look like spheres of light floating through the air. For instance, seconds before the 2009 L’Aquila, Italy earthquake struck, people observed 10-centimeter high flames of light flickering above Francesco Crispi Avenue in the town’s historical city center.
According to researchers, continental rift environments now seem to be the common factor associated with EQL. Researchers examined 65 documented EQL cases since 1600 A.D. and found that 85 percent appeared spatially on or near rifts, and 97 percent appeared adjacent to subvertical faults.
“The numbers are striking and unexpected,” posited Robert Thériault, a geologist with the Ministère des Ressources Naturelles of Québec, in a statement. ”We don’t know quite yet why more earthquake light events are related to rift environments than other types of faults, but unlike other faults that may dip at a 30-35 degree angle, such as in subduction zones, subvertical faults characterize the rift environments in these cases.”
Two of the 65 documented EQL cases that researchers studied are associated with subduction zones, but Thériault posits there may be an undiscovered subvertical fault present.
Eighty-five percent of the 65 earthquakes were greater than M 5.0. The EQL differed in shape and extent, though most frequently appeared as globular brilliant masses, either stationary or traveling, as atmospheric lights or as flame-like luminosities emerging from the ground.
The fact that EQL are seldom seen after earthquakes advances the idea that the processes responsible for EQL development are associated with a rapid build-up of stress prior to fault rupture and rapid local stress alterations during the propagation of the seismic waves.