Seismic source spectra and moment tensors （震源谱矩张量）.pdfVIP

214 Physics of the Earth and Planetary Interiors, 30 (1982) 214—227 Elsevier Scientific Publishing Company, Amsterdam — Printed in The Netherlands Seismic source spectra and moment tensors * D.J. Doornbos NTNF/NORSAR, Post Box 51, 2007Kjeller (Norway) (Received December 16, 1981; revision accepted April 6, 1982) Doornbos, D.J., 1982. Seismic source spectra and moment tensors. Phys. Earth Planet. Inter.. 30: 2 14—227. When the source spectrum is expanded in powers of frequency, the coefficient of the n th power is a linear function of the n th moment tensor. This shows explicitly the low-frequency approximation by moments of low degree, and suggests suitable ways of extrapolation. In extrapolating to higher frequencies the spectral assumption implied restricts the 2 and Gaussian models, are here considered. The source model to a particular class, and several possibilities, including w model has 20 parameters, involving moments of degree zero, one, and two. Model-dependent constraints can reduce this number to that employed in other methods. Deterministic and stochastic interpretations are given, together with the relations to source dimension and correlation length. The models considered lead to simple expressions for the displacement field and the total radiated seismic energy, and can be made to satisfy certain general properties of observed far-field spectra, including