[J07-3] Tracking the sea floor in motion III

[J07-3-02] S-net project: Large-scale seismic and tsunami observation system on seafloor along the Japan Trench

^○Kenji Uehira¹, Masashi Michizuki¹, Toshihiko Kanazawa¹, Takashi Shinbo¹, Katsuhiko Shiomi¹, Takashi Kunugi¹, Shin Aoi¹, Takumi Matsumoto¹, Shoji Sekiguchi¹, Narumi Takahashi¹, Naotaka Yamamoto¹, Masanao Shinohara², Tomoaki Yamada² (1.National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan, 2.The University of Tokyo, Tokyo, Japan)

Seafloor Observation Network for Earthquakes and Tsunamis along the Japan Trench (S-net) has 150 real-time monitoring observatories that cover the area about 1000km x 300 km from off-Hokkaido to off-Kanto. It is expected that early tsunami and earthquake warnings and earthquake researches will be enhanced. S-net consists of six segment networks of about 25 observatories and 800 km fiber optic cable (1,500 km fiber optic cable for the Japan Trench outer rise segment network). Each observatory has four sets of three-component seismometers for earthquake observation and two sets of pressure gauge for tsunami observation. Fiber-optic cable connects to landing station, and the data is transmitted from landing station to the data center via IP-VPN network.

S-net project has started in 2011. We have already finished deployment of all of the observatories and fiber-optic cables in 2016. We have also constructed five landing stations; Minamiboso station in Minamiboso City, Chiba Pref., Kashima station in Kashima City, Ibaraki Pref., Watari station in Watari Town, Miyagi Pref., Miyako station in Miyako City, Iwate Pref., and Hachinohe station in Hachinohe City, Aomori Pref.. The Watari station is located on the third floor of reinforced concrete building, and other stations are container-type data centers. The S-net (except outer-rise segment) started to operate in May 2016, and the pressure gauge and accelerometer data have been transmit to Japan Metrological Agency (JMA) for monitoring purpose. The S-net detected many earthquakes. S-net also observed tsunamis like with the earthquake of the November 22, 2016 off Fukushuma (M7.4).