Advanced Real Time Monitoring System and Simulation Researches for Earthquakes and Tsunamis in Japan - Post-Tsunami Hazard: Reconstruction and Restoration - page 173

Chapter 12
Advanced Real Time Monitoring System
and Simulation Researches for Earthquakes
and Tsunamis in Japan
Yoshiyuki Kaneda , Narumi Takahashi , Toshitaka Baba ,
Katsuyoshi Kawaguchi , Eiichiro Araki , Hiroyuki Matsumoto ,
Takeshi Nakamura , Shinichiro Kamiya , Keisuke Ariyoshi ,
Takane Hori , Mamoru Hyodo , Masaru Nakano , Jin-Kyu Choi ,
Shuhei Nishida , and Takashi Yokobiki
Abstract Mega thrust earthquakes generated large tsunamis quite often. Based on
lessons learned from the 2004 Sumatra and the 2011 East Japan Earthquakes/
Tsunamis, we recognized the importance of real time monitoring on the natural
hazards. Monitoring systems using multi kinds of sensors such as the accelerometer,
broadband seismometer, pressure gauge, difference pressure gauge, hydrophone and
thermometer is indispensable not only for mitigation of damage from earthquakes
and tsunamis, but also for understanding of broadband crustal activities around
mega thrust earthquake seismogenic zones. Therefore, we have developed the Dense
Ocean fl oor Network for Earthquakes and Tsunamis (DONET) to acquire the sea-
fl oor data in real time around the Nankai trough seismogenic zone, southwestern
Japan. The fi rst phase of deployment (DONET1) was completed and the second
phase (DONET2) is being developed at the time of writing of the manuscript. At the
2011 East Japan Earthquake, DONET1 observatories detected offshore tsunamis
15 min earlier than onshore stations. Furthermore, DONET1 and DONET2 will be
expected to monitor silent phenomena such as low frequency tremors and slow
earthquakes for the estimation of seismic stage which would occur in the inter-seis-
mic or pre-seismic stage. The recurrence cycle of mega thrust earthquakes, model-
ing of tsunami inundation and seismic response on buildings and cities are also
for Marine-Earth Science and Technology (JAMSTEC) Yohokama Institute for Earth
Sciences, 3173-25 Showa-machi, Kanazawa-ku , Yokohama 236-0001 , Japan