The proposed research will quantify the partitioning of strain between the southern Baja California continental margin and the Gulf of California seafloor spreading system through a comprehensive survey of active fault locations and slip rates at 10 to 100,000 year time scales. It builds on the experience of the PIs in the region. The focus of study is a segment of the rift margin at La Paz Bay. Several approaches will be employed, including neotectonic mapping, onshore and offshore structural mapping, paleoseismology and geodesy. The goals are to determine to what extent is the plate margin strike-slip partitioned; why does the degree of partitioning change along strike along the margin and how has faulting changed over time? The project is a part of MARGINS "rupture of continental lithosphere" initiative. Work will be in collaboration with Mexican scientists and will contribute toward the understanding of earthquake hazards in the area.