t Shirzad - PhD.Student, Science & Research Azad University
h Shomali - Assistant Professor, Institute of Geophysics, University of Tehran

Ambient seismic noise is compose of seismic waves with random amplitude and phase that can be propagated in all directions independent of a specific source. These waves have thus valuable information about the propagation path. The information which is sensitive to the Green's functions along each propagation, can then be extracted using a derivatives of the crosscorrelation and stacking methods of e.g. daily-data between two seismic stations over a long period of time. In this study, we extracted Rayleigh wave group-velocity dispersion curve at periods of 0.27-0.41 Hz (2.4 to 3.7 sec) using a phase-matched filter and frequency-time analysis techniques. After removing low-quality data, the corresponding dispersion curves have been used to calculate 1D-S velocity model for each propagation path using a non-linear inversion algorithm. The data used in this study are from TDMMO(Tehran Disaster Mitigation and Management Organization). Due to the inter-station spacing and other natural limitations of the method, we have been able to determined share wave velocity only the upper 1.8 km of the crust.

Ambient Seismic Noise, Cross-Correlation, Stacking, Dispersion Curve, Non-Linear Inversion, Shear Wave Velocity