{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,11]],"date-time":"2026-02-11T13:34:43Z","timestamp":1770816883213,"version":"3.50.1"},"reference-count":46,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2021,5,10]],"date-time":"2021-05-10T00:00:00Z","timestamp":1620604800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Total","award":["Orogen Project"],"award-info":[{"award-number":["Orogen Project"]}]},{"name":"Severo Ochoa Centre of Excellence","award":["CEX2019-000928-S"],"award-info":[{"award-number":["CEX2019-000928-S"]}]},{"name":"Junta de Andaluc\u00eda","award":["RNM-194"],"award-info":[{"award-number":["RNM-194"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The Horizontal-to-Vertical Spectral Ratio (HVSR) of ambient vibration measurements is a common tool to explore near surface shear wave velocity (Vs) structure. HVSR is often applied for earthquake risk assessments and civil engineering projects. Ambient vibration signal originates from the combination of a multitude of natural and man-made sources. Ambient vibration sources can be any ground motion inducing phenomena, e.g., ocean waves, wind, industrial activity or road traffic, where each source does not need to be strictly stationary even during short times. Typically, the Fast Fourier Transform (FFT) is applied to obtain spectral information from the measured time series in order to estimate the HVSR, even though possible non-stationarity may bias the spectra and HVSR estimates. This problem can be alleviated by employing the Hilbert\u2013Huang Transform (HHT) instead of FFT. Comparing 1D inversion results for FFT and HHT-based HVSR estimates from data measured at a well studied, urban, permanent station, we find that HHT-based inversion models may yield a lower data misfit \u03c72 by up to a factor of 25, a more appropriate Vs model according to available well-log lithology, and higher confidence in the achieved model.<\/jats:p>","DOI":"10.3390\/s21093292","type":"journal-article","created":{"date-parts":[[2021,5,10]],"date-time":"2021-05-10T10:49:51Z","timestamp":1620643791000},"page":"3292","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Horizontal-to-Vertical Spectral Ratio of Ambient Vibration Obtained with Hilbert\u2013Huang Transform"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9558-0260","authenticated-orcid":false,"given":"Maik","family":"Neukirch","sequence":"first","affiliation":[{"name":"Geosciences Barcelona, GEO3BCN-CSIC, C\/Lluis Sol\u00e9 i Sabar\u00eds s\/n, 08028 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8971-7467","authenticated-orcid":false,"given":"Antonio","family":"Garc\u00eda-Jerez","sequence":"additional","affiliation":[{"name":"Department of Chemistry and Physics, University of Almer\u00eda, Carretera Sacramento s\/n, La Ca\u00f1ada de San Urbano, 04120 Almer\u00eda, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8592-4832","authenticated-orcid":false,"given":"Antonio","family":"Villase\u00f1or","sequence":"additional","affiliation":[{"name":"Institute of Marine Sciences, ICM-CSIC, Passeig Mar\u00edtim de la Barceloneta 37-49, 08003 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7513-2791","authenticated-orcid":false,"given":"Francisco","family":"Luz\u00f3n","sequence":"additional","affiliation":[{"name":"Department of Chemistry and Physics, University of Almer\u00eda, Carretera Sacramento s\/n, La Ca\u00f1ada de San Urbano, 04120 Almer\u00eda, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0924-8980","authenticated-orcid":false,"given":"Mario","family":"Ruiz","sequence":"additional","affiliation":[{"name":"Geosciences Barcelona, GEO3BCN-CSIC, C\/Lluis Sol\u00e9 i Sabar\u00eds s\/n, 08028 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4113-2128","authenticated-orcid":false,"given":"Luis","family":"Molina","sequence":"additional","affiliation":[{"name":"Department of Biology and Geology, University of Almer\u00eda, Carretera Sacramento s\/n, La Ca\u00f1ada de San Urbano, 04120 Almer\u00eda, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,5,10]]},"reference":[{"key":"ref_1","first-page":"25","article-title":"A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface","volume":"30","author":"Nakamura","year":"1989","journal-title":"Railw. 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