faultzone

A faultzone, usually written as fault zone, is an elongated region along which rocks have fractured and been displaced by tectonic stresses. It denotes a structural zone that contains one or more faults and a surrounding damaged rock comprising broken and rearranged minerals.

Fault zones develop at plate boundaries or within plates where differential movement causes shear, extension, or compression. The zone includes a fault surface or surfaces (the fault core) and a damage zone of shattered rock that can extend tens to thousands of meters from the core. The width and complexity depend on rock type, pressure, temperature, and the history of slip.

Fault zones accommodate slip by brittle fracture and, deeper, ductile deformation. They may host seismic activity, creep, and hydrogeologic flow. Fluid pressure and mineralization influence fault strength and permeability; gouge and breccia are common in the core.

Geologists study fault zones through field mapping, stratigraphic trenching, and geophysical techniques such as seismic reflection, magnetotellurics, InSAR, and GPS to measure ground motion and deformation.

Notable fault zones include the San Andreas fault zone in California, the Alpine Fault in New Zealand, the North Anatolian Fault in Turkey, and the East African Rift system.