Shallow velocity structure using joint inversion of array and h/v spectral ratio of ambient noise: The case of Mula town (SE of Spain)

The depth of the basement and the structure of shallow sedimentary materials in Mula town (SE Spain) have been estimated applying an association of the spatial autocorrelation (SPAC) method and the horizontal-to-vertical spectral ratio (HVSR) method for ambient noise. Regular pentagonal arrays with radii up to 30 m have been employed for velocity computation. A map of predominant periods has also been obtained by applying the HVSR method to a set of 97 ambient noise measurement points of a grid, which covers the terrain equally. This map reveals a general increasing trend in the period values, from the rock outcroppings in the northern part of the town to the central and western zones where the shallow geological materials that cover the basement increase in thickness. S-wave velocity structure derived from ambient noise analysis reflects geological and geotechnical models obtained for sites where both types of raw data were available.