Synthesis of body wave seismograms from point sources in anisotropic media
- Institute of Physics of the Earth, Moscow (USSR)
A method of synthetic seismogram calculation in arbitrary anisotropic media is developed. A solution in the frequency domain is derived in the form of a double integral with respect to horizontal slowness and azimuthal angle. Approximation of the influence of azimuthal anisotropy by Fourier series expansions makes it possible to carry out the integration over azimuthal angle analytically using series coefficients derived from simultaneous linear equations. As a result the double contour integral is reduced to a Fourier-Bessel integral over horizontal slowness which retains information about azimuthal anisotropy. Numerical evaluation of this integral enables one to compute body wave seismograms with allowance for nongeometrical effects. This approach can be applied to reflection-transmission problems or to the calculation of individual wavelet propagation in multilayered anisotropic media. The influence of anisotropy on point source radiation in a homogeneous medium is analyzed. Comparison of numerical results with high frequency asymptotic solution provides a reasonable physical interpretation for wave propagation anomalies. Synthetic data for a medium of orthorhombic symmetry show that the radiation pattern and the polarization of shear waves are very sensitive to the presence of anisotropy. The most pronounced amplitude distortions are caused by focusing of energy near velocity maxima and by defocusing near velocity minima. Numerical modeling reveals significant nongeometrical phenomena in anisotropic media. In some cases deviations from geometrical seismics are substantial even in the far field.
- OSTI ID:
- 5386979
- Report Number(s):
- CONF-880531--
- Journal Information:
- Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:B7; ISSN 0148-0227; ISSN JGREA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
AMPLITUDES
ANISOTROPY
CALCULATION METHODS
DATA ANALYSIS
FOURIER ANALYSIS
GEOPHYSICAL SURVEYS
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
POLARIZATION
REFLECTIVITY
SEISMIC ARRAYS
SEISMIC DETECTORS
SEISMIC S WAVES
SEISMIC SOURCES
SEISMIC SURVEYS
SEISMIC WAVES
SEISMOGRAPHS
SIMULATION
SURFACE PROPERTIES
SURVEYS
TRANSMISSION
WAVE PROPAGATION