Project invetigates the 3 dimensional structure of the southern Basin and Range - Colorado Plateau transition zone. Project takes advantage of the pre-existing seismic data in the region, in particular 110 kilometers of data from the Safford-San Simon basin in SE Arizona. Project uses this and other data to carefully reprocess the data to extract structural information about the transition. Further interpretations are made using finite difference elastic wave modelling. Benefits will lie in the improved understanding of the structure of the southern Basin and Range - Colorado Plateau region.