Scott Smithson conducts research in reflection seismology ranging in depth and scale from shallow ground water-environmental studies to the upper mantle. His primary interest is in crustal-lithospheric structure and development. High-resolution seismology and GPR is applied to study shallow structure, groundwater karst, mine tunnels, etc. Research in petroleum exploration involves detection of new types of reservoirs from the North Sea to Venezuela to Wyoming. Both 2-D and 3-D seismic data sets are used. Research on crustal structure includes granite batholiths in Montana and Czech Republic, a core complex in Nevada, the Moho and accreted crustal terranes in SE Alaska, oldest Archean crust in the U.S in Minnesota, extended crust in West Antarctica, and crustal assemblage in the Central Rock Mountains of Wyoming. and Colorado. Seismic studies including surface seismics and VSPs at the Kola and KTB deep scientific boreholes are being studied to determine the cause of curustal reflections and seismic effects of fluids in the crust. Ultra-long range (3800 km) seismic profiles sourced by nuclear explosions in Russia are used to develop criteria for nuclear-test detection and detailed structure of the upper mantle in Eurasia. Current research emphasizes formation of continental crust, the Moho, fluids in the crust, and upper mantle heterogeneity.