Shallow shear-wave velocity structure by short period ambient noise Rayleigh wave phase velocities from beamforming and cross-correlation techniques in north-eastern Iran

We derived an average shallow shear-wave velocity model for the metropolitan Mashhad city and surrounding region in north-eastern Iran based on ambient noise Rayleigh waves dispersion curves. Phase velocity dispersions, for comparison, came from both beamforming analysis in the frequency domain as finding the average phase velocity within the array, and the spectral method of Bessell function estimations directly from Fourier transform of noise correlation functions provided in the time domain between individual station pairs of known distances across the array. Our results showed a strong agreement between two dispersion measurements. Finally, we inverted the average phase velocity dispersion curves obtained from both the beamforming and Bessel function techniques. Finally, the neighbourhood algorithm was adopted to provide an average 1D shear-wave velocity model.