Near-surface shear-wave velocity structure using time-frequency seismic noise cross-correlation in Ciudad Universitaria, Puebla, Mexico

We present a model of shear wave velocity for the botanical garden of the Beneme ' rita Universidad Aut ' onoma de Puebla in Puebla City using ambient seismic noise recorded on a geotechnical scale array. We estimate phase velocity dispersion curves of Rayleigh waves, using the Modified Spatial Autocorrelation Method (MSPAC), between 1.5 and 7.1 Hz. Also, in each station the Horizontal-Vertical Spectral Ratio was calculated (HVSR). To obtain shear wave velocity profiles, congruent with the fundamental period of the site, we carry out a joint inversion between the HVSR and the phase velocity dispersion curves under the assumption that ambient seismic noise is a diffuse field. To improve the resolution of the velocity models, we recovered the Green's function by time domain cross-correlation of ambient seismic noise in a range of 5.3-12 Hz and calculated the travel times of the wave trains between pairs of stations. Then, with depth inversions, the velocity profile at the first 25 m was estimated. Finally, the assembly of our results give rise to the improved model. The shear wave velocity model comprises five layers over a half-space reaching exploration depths of up to 215 m, according to the sensitive kernels. The resolution obtained, the depth of investigation achieved and the congruence of the models with the fundamental period of the site, make these 1D models ideal for estimating the site response to ground motions caused by seismic events.