Attenuation characteristics of Hachijojima volcano from twofold spectral ratio method using dense seismic observation

PreviousNext No AccessProceedings of the 14th SEGJ International Symposium, Online, 18–21 October 2021Attenuation characteristics of Hachijojima volcano from twofold spectral ratio method using dense seismic observationAuthors: Utako WatanabeHiroyuki AzumaYoshiya OdaUtako WatanabeTokyo Metropolitan UniversitySearch for more papers by this author, Hiroyuki AzumaTokyo Metropolitan UniversitySearch for more papers by this author, and Yoshiya OdaTokyo Metropolitan UniversitySearch for more papers by this authorhttps://doi.org/10.1190/segj2021-075.1 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract In order to interpret volcanic phenomena correctly, it is necessary to understand subsurface structure. Hachijojima Volcano, the target of this study, is an active volcano being monitored 24 hours a day by JMA. However, the subsurface structure of Hachijojima Volcano has not been clarified with sufficient resolution. The attenuation characteristics are known to be highly correlated with the properties of magma. In this study, we aim to estimate the attenuation characteristics of Hachijojima Volcano by using twofold spectral ratio method(TSRM). TSRM removes the source and site amplification characteristics by using multiple earthquake records observed at multiple stations, and extracts path characteristics, attenuation characteristics. The attenuation characteristics estimated by TSRM are average over the entire ray-path. In this study, we estimate the attenuation characteristics between seismic stations by selecting distant earthquakes whose ray-paths are almost same. Earthquake data observed by a dense seismic network of 46 stations in Hachijojima Island during the period 2019 September to 2020 March are used. In this study, we calculated the twofold spectral ratios for 13 station pairs in Nishiyama volcano and three pairs of stations in Higashiyama volcano. The low seismic attenuation area is located in the same area as dike intrusion model (Kimata, et al., 2004) and the high seismic attenuation area is situated in the area of tuff cones and tuff rings formed by phreatomagmatic explosions (Sugihara and Shimada, 1998). The high seismic attenuation regions in Nishiyama and Higashiyama volcanos roughly correspond to the low-velocity region of the velocity structure of Hagiwara and Watanabe (2019). Keywords: twofold spectral ratio, attenuation, volcano, Hachijojima volcanoPermalink: https://doi.org/10.1190/segj2021-075.1FiguresReferencesRelatedDetails Proceedings of the 14th SEGJ International Symposium, Online, 18–21 October 2021ISSN (online):2159-6832Copyright: 2021 Pages: 349 publication data© 2021 Published in electronic format with permission by the Society of Exploration Geophysicists of JapanPublisher:Society of Exploration GeophysicistsSociety of Exploration Geophysicists of Japan HistoryPublished Online: 29 Nov 2021 CITATION INFORMATION Utako Watanabe, Hiroyuki Azuma, and Yoshiya Oda, (2021), "Attenuation characteristics of Hachijojima volcano from twofold spectral ratio method using dense seismic observation," SEG Global Meeting Abstracts : 283-286. https://doi.org/10.1190/segj2021-075.1 Plain-Language Summary Keywordstwofold spectral ratioattenuationvolcanoHachijojima volcanoPDF DownloadLoading ...