Accession Number : ADA321425

Title :   Modeling of Atmospheric and Ionospheric Disturbances from Shallow Seismic Sources.

Descriptive Note : Scientific rept. no. 1,

Corporate Author : COLORADO UNIV AT BOULDER DEPT OF PHYSICS

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

PDF Url : ADA321425

Report Date : MAY 1996

Pagination or Media Count : 51

Abstract : Identification of seismic sources is enhanced by combining seismic detection methods with detection of the ionospheric disturbances caused by explosion and earthquake sources. In this study, numerical models of non-linear gravity controlled atmospheric disturbances produced by seismic sources near the surface of the earth are investigated in order to obtain quantitative predictions that can be used in evaluating detection methods based on gravity wave excitation. Explicit numerical integration of the non-linear finite difference equations is used to simulate the transient flows produced in a three-dimensional ARDC atmosphere. Results from the simulations agree with many results from linear theory approximations and also show non-linear characteristics similar to important gravity wave observations. Electron density changes in the ionosphere are predicted with their spatial and temporal behavior found to be particularly sensitive to the type and magnitude of the dissipative mechanisms that may occur. In the numerical examples studied, the amplitudes of the ionospheric electron density fluctuations due to the gravity waves produced by large explosions and some types of large earthquakes are predicted to be well within the range of detection using E-M ionospheric sounding methods.

Descriptors :   *SEISMIC DISCRIMINATION, *IONOSPHERIC DISTURBANCES, MATHEMATICAL MODELS, TRANSIENTS, EXCITATION, ELECTRON DENSITY, DIFFERENCE EQUATIONS, UNDERGROUND EXPLOSIONS, NONLINEAR DIFFERENTIAL EQUATIONS, FINITE DIFFERENCE THEORY, APPROXIMATION(MATHEMATICS), EARTHQUAKES, IONOSPHERIC MODELS, ATMOSPHERE MODELS, GRAVITY WAVES, SHALLOW DEPTH.

Subject Categories : Seismic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE