In one minute

A. Widom, J. Swain and Y. N. Srivastava explain experimental evidence that fracturing piezoelectric rocks produces neutrons. As micro-cracks build to a fracture, the piezoelectric effect turns mechanical energy into electric field energy. That energy decays through microwave-frequency oscillations of the electric field. Sound modes trapped on micro-cracks in rock oscillate at microwave frequencies, which sets the frequency of these fields. These fields accelerate electrons in the solid, which collide with protons to produce neutrons and neutrinos. Quartz-rich rocks such as granite respond strongly to mechanical disturbance, so large-scale fracturing in earthquakes brings strong electromagnetic responses.

Neutron production from the fracture of piezoelectric rocks