Tectonic Earthquakes Most earthquakes occur at plate margins due to tension, compression or shearing forces. Rocks at plate margins are in constant motion and are being pushed, pulled, bent, twisted and folded
Brittle deformation = the permanent change that occurs in a solid material due to the growth of fractures and/or sliding on fractures. A fracture is a surface of discontinuity (includes cracks, joints and faults). Faults result from shear stresses, and joints result from tensile stresses: