Where does fault collide?

A fracture in rock across which the two sides have moved measurably past each other. Structural geology treats a fault as a surface, the fault plane, along which crustal blocks slip; Anderson (1905) tied the geometry to stress, deriving normal, reverse, and strike-slip faults from the orientation of the three principal stresses and the fact that one of them stands vertical at the free surface. The referent is a physical discontinuity in the ground, and its unit is displacement, the offset of once-continuous markers measured in millimetres to kilometres. What defines it is relative motion, not the crack alone: a joint with no slip is not a fault. It shares the word with blame and with a bad tennis serve, but here it names rock that has broken and moved, and its slip rate and orientation feed directly into where earthquakes will strike.[1]

Unit

Displacement, the relative offset of once-continuous rock, plus the orientation of the fault plane

Recovery means

Not applicable

Measured by

Slip magnitude and meaning, dip and strike of the fault plane, slip rate, and the offset of marker horizons

An abnormal connection in an electrical network that lets current flow where it should not, most often a short circuit between conductors or from a conductor to earth. Power engineering calls this a fault: insulation fails or a line falls, the impedance collapses, and current surges far above the rated load until protection clears it. Fortescue (1918) gave the field its core tool, the method of symmetrical components, which resolves an unbalanced three-phase fault into balanced positive, negative, and zero-sequence sets so the fault current can be computed and the right breaker sized. The referent is a transient electrical condition, and its unit is fault current in amperes at a point in the network. It is not a broken rock and not a moral failing but a circuit doing the wrong thing, defined by where current goes rather than by any blame.[2]

Unit

Fault current in amperes, plus the faulted phases and the location on the network

Recovery means

Not applicable

Measured by

Fault current magnitude, sequence components, the impedance to the fault, and the time protection takes to clear it

Culpable responsibility for a harm: the idea that liability should rest on a defendant who was blameworthy, through intent or negligence, rather than on one who merely caused the loss. In tort law fault is the pivot on which recovery turns; Fletcher (1972) reconstructed the fault principle against strict liability, arguing that negligence law asks whether the defendant imposed a nonreciprocal risk rather than whether the act maximised utility. The referent is a normative judgment about a person's conduct, and the unit is a finding of fault or its absence, reached by a fact-finder against a standard of reasonable care. It shares the word with a slipped rock fault and an electrical short, but here nothing physical need break: fault is an attribution of blame, and a defendant can cause great harm yet bear no fault, or bear fault for a harm barely caused.[3]

Unit

A finding of fault or its absence for a party's conduct

Recovery means

Recovery of damages follows a finding of fault; no fault, no liability under a fault-based regime

Measured by

Whether conduct fell below the standard of reasonable care, judged by breach, foreseeability, and the reciprocity of the risk imposed