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Abstract:
The advance in seismic acquisition requires more techniques compatible with urban means and environmentally friendly. Accordingly, the horizontal‐to‐vertical spectral ratio (HVSR), is a method that is becoming much more popular and convenient. Used with a lot more frequency to help estimate structures and draw a better model for shallow structures. Following the tested and approved procedures described in the SESAME Project, we acquired 58 measurements in 6 profiles, including fixed and temporary stations. The study site is a strike-slip basin, called Água Bonita, located in the state boundaries of Tocantins with Goiás, in the center-North of Brazil. The deep structure of this basin is well-constrained based on geological and geophysical data. Therefore, we could compare the reliability of our depth estimates. Following the previous acquisitions, we used broadband and short-period seismometers for the acquisition, positioning the profile's location transversal to the basin length. Due to the basin geometry, we searched for a correlation between the HVSR frequency results and the sedimentary thickness, type of sediment, and overall location within the geological context. The inversion of the HVSR frequency peaks was used to estimate the depth of the layers observed. The preliminary results indicate an association between sedimentary thickness and lithology contrast. It obtained frequencies ranging from 0.2Hz at the edges to 11Hz in the basin's center. With the data acquired, we were able to trace a 3d model of the basin and possibly better identify other faults within the basin changing its geometry alongside its length.
