{"id":6125,"date":"2024-02-26T11:32:14","date_gmt":"2024-02-26T02:32:14","guid":{"rendered":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/?p=6125"},"modified":"2024-02-26T11:32:57","modified_gmt":"2024-02-26T02:32:57","slug":"detectability-analysis-of-very-low-frequency-earthquakes-methods-and-application-in-nankai-using-f-net-and-donet-broadband-seismometers","status":"publish","type":"post","link":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/research\/6125\/","title":{"rendered":"Detectability analysis of very low frequency earthquakes: Methods and application in Nankai using F-net and DONET broadband seismometers"},"content":{"rendered":"\n

Takemura, S.1<\/sup>, Baba, S.2<\/sup>, Yabe, S.3<\/sup>, Yamashita, Y.4<\/sup>, Shiomi, K.5<\/sup>, Matsuzawa, T.5<\/sup>, Detectability analysis of very low frequency earthquakes: Methods and application in Nankai using F-net and DONET broadband seismometers,\u00a0Geophysical Journal International<\/em>, 2024, 237 (1), 49-63, ggae033,\u00a0https:\/\/doi.org\/10.1093\/gji\/ggae033<\/a>
1<\/sup>ERI UTokyo, 2<\/sup>JAMSTEC, 3<\/sup>AIST, 4<\/sup>DPRI Kyoto Univ., 5<\/sup>NIED<\/p>\n\n\n\n


\u3000For a more quantitative discussion of slow earthquake activity, we evaluated the detectable limits of very low frequency earthquakes (VLFEs), which are seismic slow earthquakes observed in very low frequency (< 0.05 Hz) bands in the Nankai subduction zone. We performed numerical simulations using a local three-dimensional model and used the observed noise level of permanent broadband seismometers. First, we investigated the effects of the source-time functions on the maximum amplitudes of the VLFE signals at a certain station. The maximum amplitudes of the VLFE signals were controlled by the VLFE moment rate. The detectable limit of VLFEs at each source location can be defined as the lowest moment rate of detectable VLFEs, which radiate signals larger than the noise levels of any component at \u2265 3 stations. For inland seismometers only (Figure 1a), the detectable limits of VLFEs at deep (30\u201340 km) and shallow (\u2264 10 km) depths were 1012<\/sup>\u20131012.3<\/sup> and 1012.7<\/sup> Nm\/s, respectively. Due to the geometrical spreading of VLFE signals and large noise levels in horizontal components, offshore seismometers improved the detectability of shallow VLFEs in regions where seismometers were densely deployed (Figure 1b). Based on our detectability and published catalogs, shallow slow earthquakes are less active south-southwest off the Kii Peninsula, where geodetic studies expect mechanical coupling. The data on VLFE detectability along the Nankai Trough are uploaded at https:\/\/doi.org\/10.5281\/zenodo.7272617<\/a>.<\/p>\n\n\n\n

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Figure 1. Detectability map of very low frequency earthquakes along the Nankai Trough. Detectability using broadband seismometers (a) inland F-net only and (b) both inland F-net and offshore DONET. The triangles and diamonds are station locations of F-net and DONET, respectively.<\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"

Takemura, S.1, Baba, S.2, Yabe, S.3, Yamashita, Y.4, Shiomi, K.5, Matsuzawa, T.5, Detectability analysis of ve … Continue reading “Detectability analysis of very low frequency earthquakes: Methods and application in Nankai using F-net and DONET broadband seismometers”<\/span><\/a><\/p>\n","protected":false},"author":9,"featured_media":6126,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11],"tags":[],"class_list":["post-6125","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research"],"_links":{"self":[{"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/posts\/6125"}],"collection":[{"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/users\/9"}],"replies":[{"embeddable":true,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/comments?post=6125"}],"version-history":[{"count":2,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/posts\/6125\/revisions"}],"predecessor-version":[{"id":6128,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/posts\/6125\/revisions\/6128"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/media\/6126"}],"wp:attachment":[{"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/media?parent=6125"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/categories?post=6125"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/tags?post=6125"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}