extension fault

In geology, a fault is a fracture in Earth's crust where rocks move relative to each other due to compressional or tensional forces. These movements can range from millimeters to hundreds of kilometers.1

An extension fault, also known as a normal fault, occurs when Earth's crust lengthens, causing the rock block above the fault (the hanging wall) to slide down relative to the block below (the footwall). These faults are common and are often found in rift valleys and along the edges of mountain ranges. They can create distinctive topography like horsts (uplifted blocks) and grabens (down-dropped blocks). Examples include the East African Rift System and Death Valley.12