Abstract

CARDENAS-SOTO, Martín; RAMOS-SALDANA, Horacio  and  VIDAL-GARCIA, Martín Carlos. Seismic noise interferometry for the characterization of the 3D-velocity structure of a slope in the 3rd section of the Bosque de Chapultepec park, Mexico City. Bol. Soc. Geol. Mex [online]. 2016, vol.68, n.2, pp.173-186. ISSN 1405-3322.

In this work, we applied the seismic interferometry (SI) method in order to determine the lateral variation of S wave velocity (Vs) in the subsoil structure of a rock mass with a slope located on Joaquin Claussell Street in the 3rd Section of Chapultepec Park. Geological and geotechnical studies show that a pumice stratum, overlying semi-permeable materials, is susceptible to failure and causing a landslide due to fracturing and rains, typical factors that cause landslides in the western part of Mexico City. In order to show the applicability of the SI method to quantify the elastic properties and their distribution in the slope, we generated cross-correlation functions among 4560 pairs of receivers in an irregular array of 96 vertical geophones. By means of the temporal variations of the maximum correlation pulse, as a function of frequency (4 to 24 Hz), we built tomographic images of relative Vs velocity. We found that Vs values close to 300 m/s are related to the pumice strata, velocities that are located primarily on the slope face and at its lowest topographical level. The velocity of these materials contrasts with an underlying stratum with values greater than 1000 m/s. These results are corroborated with the soil structure derived from two seismic refraction lines. This study suggests that the SI method is appropriate to assess the geological hazards associated with slope stability.

Keywords : Landslide; slope stability; seismic refraction; surface waves; noise correlation.