Investigation of scaling properties of fault populations in the central Kenya rift

The scaling properties of 502 faults within the central Kenya rift are examined for fault populations defined from ASTER DEM data. The wide scale range of fault size populations in this study (lengths 272m – 86243km, displacement 11 - 1561m), permits detailed quantitative assessment of the scaling properties of faults and fault related strain. Three fault populations with varying trends have been defined as zone1 (NNE), zone2 (NNE to NNW) and Zone3 (NNW). Fault size populations (maximum displacement, length and geometric moment) exhibit well-defined power-law distributions in the three zones. Knowledge of the power-law exponent (fractal dimension) allows assessment to be made about the mount of deformation in a given geological setting. Slight differences in the fractal dimension (slop) of displacement population reflect strain variations across the study area. A decrease in the slop of fault population with increasing strain indicates fault evolution, which is reflected by a northward increase in the rift growth. Variations in strain localization and fault orientation in the three zones with respect to extension direction can be attributed to the influence of pre- existing structures. This influence is marked by the well correspondence of the three defined fault population zones with the pre-existing structures that were defined as heterogeneous substratum and foliations in the Precambrian basement.