Shallow slow slip events along the Nankai Trough detected by the GNSS-A

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Yusuke Yokota, Tadashi Ishikawa


Various slow earthquakes (SEQs), including tremors, very-low-frequency events, and slow slip events (SSEs), occur along megathrust zones. In a shallow plate boundary region, although many SEQs have been observed along pan-Pacific subduction zones, SSEs with a duration on the order of a year or with a large slip have not yet been detected due to difficulty in offshore observation. We try to statistically detect transient seafloor crustal deformations from seafloor geodetic data obtained by the Global Navigation Satellite System-Acoustic combination technique (GNSS-A), which enables monitoring the seafloor absolute position. Here, we report the first detection of signals probably caused by shallow large SSEs along the Nankai Trough and indicate the timings and approximate locations of probable SSEs. The results show the existence of large SSEs around the shallow side of strong coupling regions and indicate the spatiotemporal relationship with other SEQ activities expected in past studies.



Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure


GNSS-A, seafloor geodesy, Nankai Trough, long-term SSE


Published: 2019-05-16 16:39

Last Updated: 2020-01-18 06:06

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CC BY Attribution 4.0 International

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