OPERATION OF LONG-PERIOD SEISMOGRAPHS IN DEACTIVATED MISSILE SILOS.
Abstract
For a period of over six months, the Long-Range Seismic Measurements Program operated three-component long-period seismographs at the bottoms of two deactivated missile silos near Franktown, Colorado and Mountain Home, Idaho. The bottoms of these silos are approximately 150 feet below the surface. At each site, a three-component seismograph was also operated on the surface. The missile silos were found to provide operating environments superior to those of the standard LRSM long-period installations on the surface. The instruments in the silos were less susceptible to atmospheric turbulence and reacted less violently to earth loading at the surface. However, the sites in general were inherently poor locations for a 3-component long-period seismographs because they were situated on poorly consolidated sedimentary sequences. The low seismic velocities characterizing these media resulted in unusually high amplitude microseismic noise on the horizontal components and the low rigidity of the sediments made the horizontal seismographs extremely susceptible to tilt caused by local earth loading. The predominant causes of such loading was found to be strong, gusty winds. The report also discusses LRSM long-period seismograph calibration accuracy and its implications. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 28, 1968
- Accession Number
- AD0833385
Entities
People
- R. S. Simons
Organizations
- Geotech Instruments (United States)