Risk management strategy of DONET installation and the utilization of real-time data for disaster prevention

We have developed ocean floor network cable system in view of scientific and technical aspects. Japan Agency for Marine-Earth Science and Technology (JAMSTEC) already deployed a dense ocean floor network system (DONET) in the Tonankai earthquake rupture area and new one named by DONET2 in the Nankai earthquake rupture area. These earthquakes have repeatedly occurred, had tormented people living the coastal area, and suffered great damages of their strong motions and tsunami. These systems have to contribute to early detection of earthquakes and tsunamis, understanding source mechanisms of earthquakes and tsunamis, damage reduction of the coastal areas. In addition, they have to work continuously for long years even if huge earthquakes occurs, because large earthquakes with magnitude of 8 has successively occurred and because large tsunamis have also attacked accompanied with the earthquakes. To prepare such issues, we have considered in various point of views. Here we introduce such various points to set ocean floor network system and implement them.