A team investigating the strange seismic phenomenon that has been associated with multiple earthquakes around the world says the explanation may be an electronic charge created by the moving ground.
Many witnesses told of seeing white and blue lights in the sky during the 2011 Christchurch earthquake, which killed 185 people and destroyed huge parts of the New Zealand city, local newspaper The Press reported.
After the quake, cameras also reportedly captured blue flashes that have previously been unexplained.
Researchers writing in the latest issue of Seismological Research Letters have found the phenomenon is caused by a type of earthquake in which one of the Earth’s tectonic plates is pulled apart, creating a rift.
Those types of earthquakes account for only 5 percent of all quakes, as most instead occur when two plates collide.
The tension caused when two plates are pulled apart creates an electronic charge, which turns into light when it reaches the surface, the researchers said.