A Study of the Vs30 Parameter by Means of Multichannel Analysis of Surface Waves in the City of Valencia, Carabobo

Estudio del Parámetro Vs30 Mediante el Análisis Multicanal de Ondas Superficiales en la Ciudad de Valencia, Edo. Carabobo

Abstract

Average shear wave velocity in the upper 30 m (Vs30) is one of the several parameters widely used in geophysical characterization of urban areas. In addition, this represents an input of vital importance for the Seismic Microzoning Project of the main cities of Venezuela. Using the IMASW method, which combines the fundamentals of seismic interferometry and Multichannel Surface Wave Analysis (MASW), 64 ambient seismic noise lines distributed in the Metropolitan Area of Valencia (AMV) were processed to obtain 1D profiles of Vs by dispersion curve inversion. In addition, the seismic data was re-processed using the ReMi method for comparison purposes. Furthermore, these results were used to develop a Vs30 map adding on Vs30 values by topographic approximation, along with Vs30 NEHRP database, derived from SPT boreholes. By means of the Venezuelan standard COVENIN 1756-1:2019, the site classification of the Vs30 map was obtained, finding that in the urbanized soils of the study area, site class D predominates (Vs30 between 200-300 m/s), towards the center of the alluvial valleys and the lake plain, to the south of the study area. Toward the mountains, the site classes increase from CD to C. The site classes B and BC (Vs30>650 m/s) are obtained specifically in the topographic highlands that, in general, are non-urbanized mountainous areas.