felstruktur

Felstruktur, or fault structure, is a geological term that describes how faults and the surrounding rocks are organized during brittle deformation of the crust. It covers the geometry of the fault plane, the fault zone, and the rock units displaced by slip.

Key components include the fault plane, along which displacement occurs; the fault core or gouge, the crushed or clay-rich material at the center; and the damage zone, a broader region of fractured rock around the fault. The fault trace, dip, strike, and rake define its orientation and movement. Displacement magnitude is often expressed as throw, heave, or slip along the fault.

Faults are commonly classified by slip sense: normal faults (extensional regimes), reverse or thrust faults (compressional regimes), and strike-slip faults (lateral movement). Oblique-slip faults combine vertical and horizontal components. The overall architecture may include segments, jogs, and step-overs, which influence rupture propagation and seismic behavior. Faults can show complex layering, gouge composition, and irregular roughness that affect contact between rock blocks.

Formation and characteristics reflect brittle failure under stress. Near the surface, faults commonly host a rubble-filled core and fractured wall rocks, while deeper sections may juxtapose contrasting lithologies and foster mineralization along the fault zone. Segmentation, layering, and fault-rock properties control fault permeability and fluid flow, with implications for hydrothermal systems and earthquake dynamics.

Understanding felstruktur informs models of seismic hazard, resource exploration, and regional tectonics. It is studied through field mapping and trenching, as well as geophysical methods such as seismology, GPS, borehole data, and radar interferometry to image subsurface rupture and deformation.