-5the epicenter, By statistical methods using data from many stations -an epicenter may be measured with an uncertainty expressed in terms of standard deviation. This uncertainty of location does not accompany measurements of seismic disturbances from nuclear explosives. Moreover, the exact time of detonation is generally provided by the Commission, thus resulting increased accuracy of measurement. A recent publication of results in the Bulletin of Seismological Society of America provides large benefits to the seismic aspects of the AEC underground nuclear explosives program. Measurements of this kind lead not only to better evaluation of the earth's structure but also form the basis of theoretical and analytical studies in earth sciences. no data of this kind were available. Prior to the advent of testing, The present situation amounts to a major milestone in the science of seismology and brings to the AEC benefits which could not have been anticipated at the outset. The Commission shares these benefits with the scientific community and with other agencies of the United States Govermment. NUCLEAR DETECTION PROGRAM DOE ARCHIVES One of the most comprehensive programs of seismic investigations has resulted from the surveillance of clandestine underground nuclear explosions under the terms of the limited Test Ban Treaty. On both sides of the world, free and communist, elaborate systems for seismic detection have been developed and are now in constant use. These systems range from individual stations with small arrays of seismographs to very