LONG-PERIOD TESTS AT LASA SUBARRAY F3.
Abstract
A program to evaluate techniques for installing long-period seismographs is continuing at LASA subarray F3. The major tests performed during the period covered by this report include: load and tilt tests on the seismometer vault, various tank and vault sealing combinations, phase coincidence tests, temperature stability tests, and tests of the effect of wind buffeting against the vault entry. The load and tilt tests indicate that the metal tanks provide some degree of isolation from the concrete vault. Tests of vault and tank sealing indicate that as long as the vault remains sealed, only a slight reduction of background noise is realized by sealing the metal tanks housing the seismometers. Unsealing the vault resulted in a decrease of the background noise level. Some progress in understanding the probable cause of poor phase coincidence between the horizontal seismographs was made. Data show that sealing the vault reduces the temperature fluctuations within a sealed tank by as much as 20 dB. The earthen mound originally constructed over the vault entry did not reduce the wind-generated noise observed on the seismograms. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 20, 1965
- Accession Number
- AD0818284
Entities
People
- F. M. Hennen
Organizations
- Geotech Instruments (United States)