Mysterious flashes of lightning sometimes herald earthquakes, and now scientists may have discovered why: Shifting grains surrounding faults in the Earth may generate an electric charge.
This strange flickering, known as earthquake lights, can occur before or during quakes. Recent findings suggest earthquake lights seem to happen at rifts where pieces of the Earth are pulling apart from each other.
Normal lightning results from the buildup of electrical charge in clouds. However, lab experiments now suggest earthquake lights may instead originate from the buildup of electrical charge in the ground surrounding geological faults.
'Improbable' effects Applied physicist Troy Shinbrot, of Rutgers University in New Jersey, and his colleagues looked at three different kinds of particles - plastic disks, glass particles and organic powders, such as flour - that stick and slip in much the same way the Earth does in earthquake zones.
He and his colleagues study electric charge in powders, which, for example, can make pharmaceutical mixtures separate or stick to surfaces in unwanted ways in factories.