fault plane

A fault plane is a fracture in Earth's crust where rocks move relative to each other. This movement occurs due to compressional or tensional forces, causing displacement along the fracture surface, known as the fault plane. Fault planes can be vertical, horizontal, or inclined, and their angle of inclination is generally consistent along their length.1

The displacement along a fault plane can range from less than a centimeter to hundreds of kilometers. When rocks slip past each other, the block above the fault plane is called the hanging wall, and the block below is the footwall. The direction of the fault plane's intersection with the Earth's surface is the strike, and its angle of inclination from the horizontal is the dip.1

Faults are classified based on their dip angle and relative displacement. For example, strike-slip faults involve horizontal movement parallel to the fault plane, which is typically vertical. Earthquakes are often caused by the sudden release of energy along fault planes.23