Effects of a descending lithospheric slab on yield estimates of underground nuclear tests. Final technical report, 8 Mar 88-31 Aug 90

Technical Report · Fri Feb 01 00:00:00 EST 1991

OSTI ID:5231906

Cormier, V F; Kim, W; Mandal, B; Harvey, D

A method for computing seismic wavefields in a high-frequency approximation is proposed based on the integration of the kinematic ray tracing equations and a new set of differential equations for the dynamic properties of the wavefront, which the authors call the vicinity ray tracing (VRT) equations. These equations are directly obtained from the Hamiltonian in ray centered coordinates, using no paraxial approximations. This system is comparable to the standard dynamic ray tracing (DRT) system, but it is specified by fewer equations (four versus eight in 3-D) and only requires the specification of velocity and its first spacial derivative along a ray. The VRT equations describe the trajectory of a ray in ray centered coordinates of a reference ray. Quantities obtained from vicinity ray tracing can be used to determine wavefront curvature, geometric spreading, travel time to a receiver near the reference ray, and the KMAH index of the reference ray with greater numerical precision than is possible by differencing kinematically traced rays. Since second spatial derivatives of velocity are not required by the new technique, parameterization of the medium is simplified, and reflection and transmission of beams can be calculated by applying Snell's law to both vicinity and central rays. Conversation relations between VRT and DRT can be used to determine the paraxial vicinity of DRT, in which the errors of the paraxial approximations of DRT remain small. Because no paraxial approximations are made, the superposition of the Gaussian beams define from the vicinity rays should exhibit a much slower breakdown in accuracy as the scale length of the medium given by V/Delta v approaches the beamwidth.

• Research Organization: Connecticut Univ., Storrs, CT (United States). Dept. of Geology and Geophysics
• OSTI ID: 5231906
• Report Number(s): AD-A-235569/1/XAB; CNN: F19628-88-K-0010
• Country of Publication: United States
• Language: English

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45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
NUCLEAR EXPLOSIONS
YIELDS
ACCURACY
CALCULATION METHODS
COORDINATES
DIFFERENTIAL EQUATIONS
DYNAMICS
EARTH CRUST
EQUATIONS
HAMILTONIAN FUNCTION
LENGTH
PLATE TECTONICS
SEISMIC DETECTION
SEISMIC WAVES
SPATIAL DISTRIBUTION
SPECIFICATIONS
TESTING
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UNDERGROUND EXPLOSIONS
VELOCITY
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DIMENSIONS
DISTRIBUTION
EXPLOSIONS
FUNCTIONS
MECHANICS
TECTONICS
450200* - Military Technology
Weaponry
& National Defense- Nuclear Explosions & Explosives