HVSR analysis of pumice sands for sediment depth characterization: A case study for Guadalajara, Mexico

Abstract

The horizontal to vertical spectral ratio (HVSR) methodology is used here to characterize pumice soils and to image the three-dimensional surface geometry of Guadalajara, Mexico. Similar to other Latin American cities, Guadalajara is exposed to high seismic risk, with the particularity of being the largest urban settlement in Latin America built on pumice soils. Methodology has not yet been tested to characterize subsoil depths in pumice sands. Due to the questionable use of traditional geotechnical tests for the analysis of pumice soils, HVSR provides an alternative for its characterization without altering its fragile and porous structure. In this work, resonance frequency (F₀) and peak amplitude (A₀) are used to constrain the depth of the major impedance contrast that represents the interface between bedrock and pumice soil. Results were compared with borehole depths and other available geotechnical and geophysical data and show good agreement. One of the profiles estimated on the riverbanks that cross the city, reveals different subsoil thickness that could have an impact on different site responses on riverine areas to an eventual earthquake. Government and academic efforts are combined in this work to characterize depth sediments, an important parameter that impacts the regulations for construction in the city.