Characterization of landslides in Federal Highway 1D, Baja California, Mexico, using seismic noise records and the HVSR method

A landslide is a natural phenomenon that can cause several damages, including life and economic loss. Highway 1D (toll highway) communicates the cities of Tijuana and Ensenada in Baja California, Mexico. Since its construction, several landslides have affected the route between the zones at km 90 + 000 and 98 + 300. On December 28, 2013, one of the largest events affected the location at km 93 + 500, causing a collapse of the highway with a length of more than 300 m. A thorough study of landslides in this region has been carried out from the geological and geophysical point of view, using electrical resistivity and LiDAR methods. In this work, we propose the use of seismic noise analysis for the subsoil characterization of the area, considering the horizontal-to-vertical spectral ratio (HVSR) methodology. We invert the HVSR curve to characterize two landslide zones on highway 1D, to obtain the V-P (compressional wave velocity) and V-S (shear wave velocity) velocity profiles. The notorious velocity contrast within the first meters allows us to infer the areas more susceptible to slip. The high values of V-P/V-S ratios confirm the high fluid content within the landslide areas, which could accelerate the sliding process. The high-frequency peaks indicate zones with high material accumulation, which can be associated with unstable soil.