We present MD simulations of shear cells of a densily packed array of
polygonal grains in two dimensions. We study the dependence of the she
ar force on the shear velocity. Generally shear hardening is observed.
The dependence of the dilatancy on the shear velocity is measured, We
also apply the method to simulate two tectonic plates moving under sh
ear. We find a Gutenberg-Richter-like law with a b-value of (1.02 +/-
0.06) in good agreement with geophysical measurements. Shear bands of
widths dependent on the confining pressure and the shear velocity are
observed.