Tectonic processes occurring in shallow subduction zones around the world generate the majority of large, damaging earthquakes. Last decade brought more understanding of these processes, showing their complexity and diversity from place to place. A full understanding of the seismotectonics of shallow subduction zones is yet to be achieved - however, the ambitious goal of forecasting at least the largest of earthquakes is certainly worth pursuing. This volume reports the most recent research in this field and includes theoretical, as well as observational, works concerning seismicity, mechanics and seismic potential of subduction segments around the world. Topics covered in Part 1 include: slip partitioning along major plate boundaries; quantitative estimates of interplate coupling; estimates of seismic potential for segments along central and South America, and case studies of a few large earthquakes.