The objective of this study is to determine why a significant fraction of the slip on oceanic transform faults occurs by aseismic creep rather than by earthquakes. The study will test the hypothesis that this behavior is due to the existence of serpentine along the transform faults. If serpentine exhibits velocity hardening, then the serpentine will accommodate the movement along the faults through aseismic creep. A series of experiments will be conducted to determine the frictional constitutive behavior of serpentine, as well as a more exploratory series of experiments to determine the constitutive behavior of basalt and peridotite. Then a realistic fault instability model for oceanic transform faults will be constructed. Together these experiments are expected to result in an understanding of the observed combination of seismic and aseismic slip on oceanic transform faults.