ABSTRACT
Okinawa, which is located in the southwest part of Japan, is tectonically very active. Ryukyu subduction zone is characterized by the subducting Philippine Sea plate beneath the Eurasian plate and by crustal extension at the back of the arc in the Okinawa Trough. Historically, Okinawa region have been ex-perienced the severe damage of earthquake and tsunami several times. At the present day, a great numbers of seismographs are deployed on Ryukyu arc islands by Japan Meteorological Agency (JMA) and other au-thorities to monitor the seismic activities for the purpose of disaster mitigation and various researches.
