Spectra of Seismic Waves from Underground Explosions from Observations in the Near Zone
Abstract
Analysis of frequency spectra for ground oscillations in the near zone of an explosion indicates a simple shape with a simple well-defined maximum at 1.2-2 hertz. The frequency of the maximum is but two-thirds to one-half the apparent frequency of the domal uplift of the ground. Analysis of soil displacement relative to distance makes it possible to outline the near zone of the explosion, where nonelastic deformation takes place. The frequency spectra from eruptive explosions differ from similar spectra of underground (confined) explosions in width, amplitude, and frequency of the maximum. The relative width of the R-wave spectrum for confined explosions is about 80 to 90 percent that for explosions with ejected material. The frequencies of the maximums are 1.5-2.2 and 1.7-4.6 hertz, respectively. Frequency of the spectral maximum differs from the visible frequency by 20-30 percent. The velocity spectra for longitudinal waves change in frequency of the maximum, depending on size of charge: from 9 to 17 hertz for confined underground explosions, from 4 to 23 hertz for cratering explosions (with ejecta).
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 20, 1970
- Accession Number
- AD0717880
Entities
People
- N. V. Kuzmina
Organizations
- National Air and Space Intelligence Center