Geodynamics and Tectonics Plate Analysis based on Distributed Optical Fibre Acoustic Sensor

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Megathrust earthquakes have long occurred repeatedly in Japan. Since 2011, an oceanic observation networks constituted by point sensors connected by optical fibres have been developed to monitor seismotectonic activities in this region. In this project we expand the seismometer capabilities by using the optical fibre network itself as a distributed seismometer providing thousands of high resolution seismic measurements aimed at clarifying the source of the very low frequency earthquakes based in the accretionary wedge between the Philippine Sea Plate and the Eurasian continent, which were discovered by the DONET stations in 2015.After initial tesing in JAMSTEC own fiber optic cables off Toyohashi, Aichi, Japan and Hatsushima, Shizuoka, Japan, a portable unit will be manufactured and will be taken on the research vessel R/V Shinsei-maru to be connected to the 10 km fibre optic extension cables via a fibre optic cable of the shipboard remotely operated vehicle. The novel distributed seismometer will be tested in the DONET stations to produce a 3D map of seismic activity along the Nankai through and investigate possible links links with the structure of the subducting plate interface.