Ground motion measurements to support the DOE-NV safety program

In support of DOE-NV's safety program, URS/Blume is conducting a seismic documentation program with the primary objective of measuring, for analysis and evaluation, the ground and structural-response motion resulting from underground nuclear explosions (UNEs). Until 1979, instruments were deployed to record seismic activity originating outside the NTS as well, but deployment is now limited to the communities surrounding the NTS. The majority of the instruments are now installed in the high-rise buildings that have proliferated in Las Vegas in recent years. Our seismic-motion measuring equipment varies from accelerographs that record motion on photographic paper to systems that digitize and record data on cassettes. However, our basic workhorse is the L-7 velocity meter system, which records up to 12 channels of data on FM tape. Depending on need, site accessibility, and type of system, either source motion or a radio trigger activates the system. The system can also record continuously. On one building, a laser was used to record both transient and steady-state motion. Data processing centers around a minicomputer. In the current configuration, analog and digital playback equipment is integrated into the total processing system. The minicomputer performs basic processing, such as peak amplitude scaling; signal conditioning; differentiation and integration; and generation of response spectra. More complex analysis is done on larger computers elsewhere. The results are useful to various DOE-NV support groups. 12 references, 19 figures