https://scholars.lib.ntu.edu.tw/handle/123456789/412272
標題: | Traveltimes of waves in three-dimensional random media | 作者: | Baig, A. M. Dahlen, F. A. Hung, Shu-Huei |
關鍵字: | Body waves | Inhomogeneous media | Ray theory | Tomography | Traveltime | Wave propagation | 公開日期: | 1-五月-2003 | 卷: | 153 | 期: | 2 | 起(迄)頁: | 467 | 來源出版物: | Geophysical Journal International | 摘要: | We present the results of a comprehensive numerical study of 3-D acoustic wave propagation in weakly heterogeneous random media. Finite-frequency traveltimes are measured by cross-correlation of a large suite of synthetic seismograms with the analytical pulse shape representing the response of the background homogeneous medium. The resulting 'ground-truth' traveltimes are systematically compared with the predictions of linearized ray theory and 3-D Born-Fréchet (banana-doughnut) kernel theory. Ray-theoretical traveltimes can deviate markedly from the measured cross-correlation traveltimes whenever the characteristics scalelength of the 3-D heterogeneity is shorter than half of the maximum Fresnel zone width along the ray path, i.e. whenever a ≲ 0.5(λL)1/2, where a is the heterogeneity correlation distance, λ is the dominant wavelength of the probing wave, and L is the propagation distance. Banana-doughnut theory has a considerably larger range of validity, at least down to a ≈ 0.1 (λL)1/2 in sufficiently weakly heterogeneous media, because it accounts explicity for diffractive wave front healing and other finite-frequency wave propagation effects. |
URI: | https://scholars.lib.ntu.edu.tw/handle/123456789/412272 | ISSN: | 0956540X | DOI: | 10.1046/j.1365-246X.2003.01905.x |
顯示於: | 地質科學系 |
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