Displacement Length Scaling Relationship for Faults - Data Synthesis and Discussion

It is observed that the amount of displacement (d) on a fault is proportional to the mapped trace length L. The exact form of the fault scaling relationship, i.e. d = f(L), is still a subject of some disagreement. A number of workers have interpreted data from individual data sets as indicating a linear relationship between d and L. However, these individual data sets have large scatter and a limited range of scale, so their interpretations are not fully conclusive. Other workers have interpreted combinations of different data sets, taken together, and concluded that the d vs L scaling relationship is non-linear. Fault growth models, however, indicate that the scaling relationship should depend on rock properties so correlations using combined data sets may be questionable.This paper presents a synthesis of published data sets on the displacements and lengths of faults. A summary of each data set is given, including: the geologic setting; the mode of faulting (normal/thrust/strike-slip); and the measurement methods used to obtain the displacement and length data. Sources of scatter in the data due to geologic effects and measurement procedures are reviewed. Our preferred interpretation is that the d-L relationship is linear with a possible cross-over phenomenon between small and large faults, but the unambiguous resolution of this question will require some significant improvements in the existing database.