DEMETRA – Dense Maccalube Tromino Acquisition – Horizontal-to-Vertical Spectral Ratio (HVSR) and Polarization Parameters Description:This dataset contains Horizontal-to-Vertical Spectral Ratio (HVSR) curves and the polarization parameters from seismic noise recordings collected during the DEMETRA (DEnse MaccalubE TRomino Acquisition) field survey, which was conducted on 22–23 April 2025 at the Maccalube di Aragona mud volcanoes (Southern Italy). The HVSR curves were computed using the Grilla Rel. 9.9.0 software package (https://www.tromino.it/frameset-grilla.htm), starting from the raw Tromino® recordings (https://doi.org/10.5281/zenodo.17617939) acquired at 21 sites (DMT01–DMT21). Each file in this dataset corresponds to one measurement point and is provided in ASCII format, containing both acquisition metadata and spectral quantities. The filename indicates the site ID (for example: HV_DMT_1.asc). Polarization parameters were estimated using the covariance matrix method, in two frequency bands: 0.2–1 Hz and 1–5 Hz. Each file corresponds to one measurement site and one frequency band. The filename indicates the site ID and the frequency band (for example: DMT01_pol_0.2_1Hz.dat; DMT01_pol_1_5Hz.dat). The methodological details are described in: Petrosino, S., Madonia, P., Gucciardo, D., & Cusano, P. (2025).DEMETRA—A Seismic Noise Survey at the Maccalube di Aragona Mud Volcanoes (Southern Italy): Results and Perspectives. Sensors, 25(22), 6975.DOI: https://doi.org/10.3390/s25226975