Accession Number : ADA258597


Title :   Investigations of Joint Seismic and Electromagnetic Methods for Nuclear Test Monitoring


Descriptive Note : Scientific rept. no. 1


Corporate Author : COLORADO UNIV AT BOULDER DEPT OF PHYSICS


Personal Author(s) : Archambeau, Charles B ; Davies, John B ; Orrey, Jeffrey


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a258597.pdf


Report Date : 15 Feb 1992


Pagination or Media Count : 70


Abstract : This study is designed to develop both linear and non-linear modeling methods for prediction of excitation of atmospheric and seismic disturbances from near surface explosions and earthquake sources in complex media which include strong lateral variability, randomness and non-linear response effects. Comparisons with observations are systematically pursued to evaluate these models and to develop source discrimination methods. In this report we describe examples of non-linear atmospheric excitation by near surface explosions which are carried to ionospheric heights in order to predict fluctuations in ionospheric electron densities and ionization layer positions. These predictions are compared to active EM monitoring by ground stations of ionospheric layer perturbations due to the large amplitude atmospheric waves from surface explosions. We also consider atmospheric turbulent coupling at the earth's free surface and investigate the high frequency seismic noise characteristics resulting from this source using combined seismic and atmospheric modeling. Results are in first order agreement with spectral observations of high frequency noise, in that both the theoretical and observed particle velocity spectra vary as 1/f in the high frequency range from 1 to 50 Hz. Examples of the effects of randomness, large scale lateral variations and near source surface topography on the seismic wave field from near surface explosions are systematically investigated. We find good first order correlations of predictions with the complex regional and near field observations using reasonable structure/topographic models.


Descriptors :   *SEISMIC WAVES , *EARTHQUAKES , VELOCITY , NUCLEAR EXPLOSIONS , IONOSPHERE , HIGH FREQUENCY , PREDICTIONS , ELECTRON DENSITY , EXPLOSIONS , GROUND STATIONS , ATMOSPHERE MODELS , AMPLITUDE , PERTURBATIONS , ATMOSPHERIC DISTURBANCES , ELECTROMAGNETIC WAVE PROPAGATION , TOPOGRAPHY , EXPLOSION EFFECTS , SPECTRA , WAVE PROPAGATION


Subject Categories : Seismology
      Nuclear Weapons


Distribution Statement : APPROVED FOR PUBLIC RELEASE