Abstract - Maximum total displacement (D) is plotted against fault or thrust width (W) for 65 faults, thrust, and groups of faults from a variety of geological environments. Displacements range from 0.4m to 40km and widths from 150m to 630km, and there is a near linear relationship between D and W2. The required compatibility strains es in rocks adjacent to these faults increases linearly with W and with (SQR)D and ranges from es=2x10-4 to es=3x10-1. These are permanent ductile strains, which compare with values of es=2x10-5 for the elastic strains imposed during single slip earthquake events, which are characterised by a linear relationship between slip (u) and W.
The data are consistent with a simple growth model for faults
and thrusts, in which the slip in successive events increases by increments
of constant size, and which predicts a relationship between displacement
and width of the form D=cW2. Incorporation of constant ductile
strain rate into the model shows that the repeat time for slip events remains
constant throughout the life of a fault, while the displacement rate increases
with time. An internally consistent model with es=2x10-5,
giving repeat times of 160 years and instantaneous displacement rates of
0.02cm/yr, 0.2cm/yr, and 2.0cm/yr when total displacement is 1m, 100m,
and 10km, and slip increasing by 0.5mm with each event, gives a good approximation
of the data. The model is also applicable to stable sliding, the slip rate
varying with ductile strain and with W2.
Pure and Applied Geophysics 124, 365-373, 1986.