March 13 (UPI) -- A new study led by Britain's University of Plymouth offers insight on the mechanisms behind earthquakes 25 or more miles below the surface.
Little is known about deep earthquakes, largely because their effects are generally hidden underground, but the study suggests that ruptures may be encouraged by the interaction of different shear zones moving slowly and aseismically, indicating movement without accompanying seismic shock. The interaction loads the adjacent blocks of stiff rocks in the deep crust until they can no longer sustain the rising stress, and a rupture prompts an earthquake. The study suggests that slow but repeating cycles of deformation on the shear zones bring accumulated stress, punctuated by episodic earthquakes.