-3oil and gas of the world are now being discovered. Since 1926, surveys for these goals have covered most of the continental areas of the world and are now reaching into marine environments where valuable fuel deposits have been developed beneath the oceans. Other applications are being made in the search for mineral commodities and ground water. The seismograph has become a major, indispensable tool of industry over the entire world, Without the incentive of these immediate economic goals, use of the seismograph with explosives has also led to solution of complex geological problems throughout the world. By interchange of information among various disciplines such as earthquake seismology, exploration seismology and geologic napping, many geological details of the earth's erust have been determined which provide valuable scientific resources for future developments of many kinds. THE AEC NUCLEAR TESTING PROGRAM Of immediate interest to you who are assembled here today is the use of underground nuclear explosives to reach the goals of the Atomic Energy Commission and other agencies of the United States Govermment. The testing program at the Nevada Test Site and elsewhere has provided the world with an unprecedented amount of reliable accurate seismic data. These data have been provided by the Commission in such form that their use has become widespread in the solution of majobQE-ARCHIVES science problems. Improvements in understanding the complex structure of the earth, the mechanisms of seismic wave generation and propagation have been accomplished through better instrumentation systems, the 22