Frictional fusion occurs during high strain-rate events and is recorded by pseudotachylyte. Thus potentially, this material may provide information on several parameters of the brittle faulting process that are currently difficult to obtain, such as frictional temperature attained, the presence of a fluid during faulting and degree of elemental and isotopic reequilibration attained `efore quench. This research will utilize electron microbeam techniques and laser heating isotopic methods to examine these factors in natural and synthetic pseudotachylyte. Results have the potential of yielding significant insight into the factors attending frictional fusion, and therefore could provide a tool for understanding the behavior of brittle faults in the high strain-rate or seismogenic regime.