This award provides approximately one-half the funds needed to acquire an optical mass storage module to be installed in the Department of Earth and Planetary Sciences at Harvard University. The storage system has a capacity of 165 gigabytes and will be controlled by a computer which can be accessed by the Harvard university-wide Ethernet system and the national NSFnet system. Digital seismograms recorded by the global seismic network since 1972 already constitute approximately 100 gigabytes of scientific data with many potential applications such as studies of seismic sources and deep-earth tomographic imaging. The data set is very large and growing, and it currently resides on 5000 magnetic tapes. Direct, on line, access to this data transferred to the optical storage system is the only practical means of scientifically processing this resource.