Abstract - The distinct element method is used for modeling the growth of normal faults in
layered sequences. The models consist of circular particles that can be bonded together
with breakable cement. Size effects of the model mechanical properties were studied for a
constant average particle size and various sample widths. The study revealed that the
bulk strength of the model material decreases with increasing sample size. Consequently,
numerical lab tests and the associated construction of failure envelopes were performed for
the specific layer width to particle diameter ratios used in the multilayer models. The
normal faulting models are composed of strong layers (bonded particles) and weak layers
(nonbonded particles) that are deformed in response to movement on a predefined
fault at the base of the sequence. The modeling reproduces many of the geometries
observed in natural faults, including (1) changes in fault dip due to different modes of
failure in the strong and weak layers, (2) fault bifurcation (splaying), (3) the flexure of
strong layers and the rotation of associated blocks to form normal drag, and (4) the
progressive linkage of fault segments. The model fault zone geometries and their
growth are compared to natural faults from Kilve foreshore (Somerset, United Kingdom).
Both the model and natural faults provide support for the well-known general trend that
fault zone width increases with increasing displacement.
Journal of Geophysical Research 112, B10401, 2007.