Rocks deform either by permanent, gradual (ductile/plastic) flow or by sudden fracture (brittle failure) once stress exceeds the rock's strength. Earthquakes are the seismic energy release associated with sudden slip on a fault surface — the hallmark of brittle deformation.
An earthquake occurs when accumulated elastic strain energy along a fault is suddenly released as the rock on either side of the fault fractures and...
Full option-by-option analysis available to enrolled students.