An Expression of the Cross-Correlation of Ambient Seismic Noise： A Derivation Based on the Surface-Wave Theory

详细信息   

• 责任者：Zhu Liangbao (Dept. of Geophysics ; School of Geodesy and Geomatics ; Wuhan University ; Wuhan 430079 ; China) ; Wang Qingdong
• 刊名：Chinese Journal of Geophysics
• 出版年：2011
• 卷期：54(7)
• 关键词：地震勘探 ; seismic exploration ; 噪声 ; noise
• 页码：p.1835-1841
• 图表：4 illus., 19 refs.
• 分类号：1600
• issnNo：ISSN0001-5733
• isbnNo：CN11-2074/P

摘要

The present study derives the surface-wave theoretical expression ot the noise cross- correlation function （NCF）. We demonstrate that the NCF is equivalent to the surface-wave excitation, in which the equivalent source is at one of the two stations. The most important concept of this paper is the equivalent source＇s phase function, which directly influences the accuracy of group and phase velocity measurements. Under a homogenous source distribution assumption the equivalent source＇s phase is П/4. In general, it is dependent on the distribution of noise sources, instead of being a constant. Under the condition of large signal to noise ratios （SNR）, the possible maximal value of the equivalent source＇ phase is equal to SNR＇s reciprocal. This paper also tries to study the possibility of using three stations to measure phase velocities and to estimate the equivalent sourcet s phase {unction and then gives the measurement errors.