Study of extracting group velocities of near-surface Rayleigh waves from ambient noise

摘要

Traditional estimation of seismic waves velocities in Earth's interior is based on observation of waves imposed by natural earthquakes or human made explosions. The observation of seismic waves is limited in some places, where the probability of occurrence of natural earthquakes is small, the activity of plates is extremely stable or the seismic waves attenuation is too serious. In recent years a new method to measure the group velocities of Rayleigh waves using cross-correlation analysis of ambient noise has been presented, which largely break of the limitation of above, it does not depend on the natural occurrence of the earthquake, and can provide more information of short periods and shallow structure of the earth, and is successfully used in various areas in the world. Velocities tomography of ambient noise has shown strong vitality not only in the applications of large scale, but also in small scale. In this paper, empirical Green's runctions(EGF) of Rayleigh surface waves is extracted through the calculation of ambient noise crosscorrelation,which used three-components ambient noise experimental data of 12 receivers, that is acquired in October 15, 2009. The group velocities curve of Rayleigh surface wave is gotten and the method of extracting group velocities of near-surface using ambient noise is discussed in small scale within 100 meters.