What is shear and where in the crust is this likely to occur?
Shearing is a force tending to cause deformation of a material by slippage along a plane or planes(areas) parallel to the imposed stress. The resultant shear creates a large effect in nature, being closely related to the downslope movement of earth materials, and to earthquakes.
Ultimately, shearing can happen anywhere there is enough pressure being exerted on the crust. However, the most likely location for a shear is a fault line.