Recent geologic and geodetic data indicate that a zone, termed the Eastern California shear zone, of right lateral shear has been long-lived and is still active. However, within the shear zone, there is conflicting evidence of which strand is active-geologic data require that the Death Valley-Furnace Creek fault zone is the principal locus of shear, while geodetic data appear to favor the Owens Valley fault. Of the several possible explanations of this paradox, this project will test the model that the locus of shear is currently in the process of shifting from the former to the later. The results are also expected to improve understanding of the fundamental mechanisms that control fault interactions and slip partitioning between parallel strike-slip faults and connecting normal faults.