We use a specific set of symbols to identify faulting geometry on maps. A focal mechanism is a graphical summary the strike, dip, and slip directions. The focal mechanism shows the view of the hemisphere from directly above. Some example focal mechanisms are shown below. Stress and Strain Stress is a force per unit area or a force that acts on a surface.
Friction is a stress which resists motion and acts in all natural systems.
Strain is a measure of material deformation such as the amount of compression when you squeeze or the amount of elongation when you stretch something. In elastic deformation the amount of elongation is linearly proportional to the applied stress, and an elastic material returns to its original shape after the stress is relieved. Additionally, a strained, elastic material stores the energy used to deform it, and that energy is recoverable. As you know, some regions repeatedly experience earthquakes and this suggests that perhaps earthquakes are part of a cycle. The effects of repeated earthquakes were first noted late in the nineteenth century by American geologist G. K. Gilbert.