9405870 Edwards This research, which is a collaboration between the California Institute of Technology, the University of Minnesota and the University of Texas, is a study of the two great plate-boundary faults of Sumatra. Preliminary studies funded by the NSF demonstrate the high potential of these projects. The work addresses fundamental questions concerning both the repeatability of great earthquakes and the kinematics of obliquely convergent plate boundaries; results would apply to earthquake hazard at plate-boundary faults in the U.S. in California, the Pacific Northwest and Alaska. The goals are 1) to use submerged and emergent late Holocene corals to map and to date vertical deformations associated with great historical, ancient and future earthquakes of the Sumatran subduction zone and 2) to complete a neotectonic map of the right-lateral strike-slip Great Sumatran fault and to determine its late Quaternary rates of slip. This research is a component of the National Earthquake Hazard Reduction Program. ***