MULTICOMPONENT STRAIN SEISMOGRAPH
Abstract
Spectra of microseisms recorded by the vertical strain, crossed horizontal strains, and their summation were examined to determine the similarity of the outputs of the strain seismographs. Only at spectral peaks were the vertical and crossed horizontal strains found to have about equal response. A preliminary examination of the ability of the north and east summed horizontal strain and inertial seismographs to reject microseisms was undertaken employing spectra. Reduction of about 10 dB was attained for single source microseisms. The conclusion that true earth strain is being recorded by the vertical strain seismometer is supported by two results: (1) Rayleigh waves at 1 cps are cancelled by at least 15 dB by summing vertical strain and vertical inertial seismograph outputs; (2) the empirical value of the ratio of vertical strain to summed orthogonal horizontal strain is within 12 percent of the theoretical value for Rayleigh waves at 1 cps.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 19, 1966
- Accession Number
- AD0803202
Entities
People
- Robert C. Shopland
Organizations
- Geotech Instruments (United States)