Estimation of S-wave Velocity Profiles of Deep Sedimentary Layers in Metropolitan Lima Using Seismic Interferometry

Eight shear wave velocity profiles of deep sedimentary layers in Lima, Peru, were determined using seismic interferometry. To achieve this objective, seven high-sensitivity sensors monitoring continuous ground motion were installed. Sensor data allowed the extraction of Green’s functions through cross-correlation analysis in the frequency domain. It was determined that continuous recording data with a minimum of 2,000 h (equivalent to three months) is necessary to obtain a Green’s function approximation. Dispersion curves of surfaces from 0.3 to 2 s were obtained from maximum values of Green’s functions between two stations after applying Gaussian filters. Thus, obtaining deep soil profiles through the inversion of dispersion curves extended to periods of around 1 s is possible. Finally, the estimated profiles were verified by comparing their theoretical ellipticity curves with H/V spectral ratios of microtremors, finding a good match for periods up to 1 s. These profiles reach depths and S-wave velocities of up to 600 m and 3,000 m/s, respectively.