Shifting grains may explain earthquake lightning

DENVER— Beads and flour could help explain a rare and mysterious phenomenon: lightning strikes called earthquake lights that occur before or during major quakes. New results presented March 6 at an American Physical Society meeting demonstrate that shifting granular materials, which simulate earth along a fault, can induce remarkably high electric voltages.

A few years ago, physicist Troy Shinbrot of Rutgers University in Piscataway, N.J., developed a simple experiment to determine whether earth under stress could create conditions favorable for lightning above the surface. When he tipped a container of flour, a sensor inside registered an electrical signal on the order of 100 volts (SN: 7/14/12, p. 13).